Tài liệu Questions for revision - English for mechanical engineering ppt

Questions for revision- English for mechanical
engineering
I. Tr¾c nghiÖm
1 Brass is an of copper and zinc.…………………
A. alloy B. avoid C. mixture D. part
2 Aluminum, copper and bronze don’t contain iron. They are metals…………
A. iron B. not iron C. ferrous D. non ferrous
3 Metals which contain some proportion of iron may be attacked by …………
A. other metals B. corrode C. rust D. rustion
4 High-purity metal are more resistant than .……………………
A. alloys B. iron C. metals D. ferrous metals
5 What is the width of the bolt? It is 2cm .……………………
A. wide B. width C. in wide D. at width
6 A diesel engine is an engine which uses ……………
A. oil B. diesel C. diesel oil D. diesel petrol
7 Which view is taken to show the most important or descriptive face?
A. front view B left view. C. top view D. bottom view
8 The view obtained by looking at the object from below is called…………
A. front view B left view. C. top view D. bottom view
9 An industrial drawing comprises several separately placed figures known as ………
A. observers B views C. directions D. figures
10 The view in drawing is the image of the face of the closest to the observer.………………
A. observer B object C. obtain D. subject
11 What do we call the tolerance which allows deviations from it in both sides?
A. two side B unilateral C. bilateral D. one side
12 Designer who work with CAD don’t need to produce drawings on …………
A. computer B picture C. figure D. paper
13 What is one ten thousand mean?
A.10,000 B. 1000/10 C. 1/10000 D. 10/1000
14 Which is used primarily to measure the hole diameter?
A. outside caliper B. inside caliper C. hermaphrodite

caliper
D. caliper
15 In the smallest hole is bigger than the largest shaft.…………
A. interference fits B. clearance fits C. mating parts D. engineering
16 The interior fitting parts are known as ………………………
A. shafts B. dimension C. diameter D. holes
17 The person who creates new products on paper or with CAD is a/an ……………………
A. design engineer B. installation engineer C. production engineer D. technician
18 A tensile force is a force which can .a body.………
A. compress B. push C. make D. extend
19 Physical quantities are divided into groups- scalar and vector quantities.
A. added B. classified C. subtracted D. multiplied
20.The length of the vector is to the magnitude of the force it represents.……………
A. proportional B. opposite C. equal D. longer
21 The intensity of stress depends on .…………………
A. c.s.a B. size of the force C. stress D. both A and B
23 Distortion due to stress is called……………………
A. strain B. stress C stress and strain. D. tensile
23 Mild steel is material.……………
A. a plastic B. an elastic C a tough D. a corrosion-resistant
24 material can regain its shape and size after the forces are removed.…………
A. rigid B. elastic C tough D. plastic
25 A/An .substance can be used to wear away a soften material.………
1
A. formable B. organic C abrasive D. ductile
26 If a material is .it will tend to fracture under impact loads.……………
A. rigid B. brittle C hard D. elastic
27 The point the body is free to rotate is called the fulcrum.…………
A. which B. in which C about which D. that
28 The point where the effort is applied to a lever is called.

A. effort end B. load end C fulcrum D. rest end
29 A bent shaft for transmitting motion , changing from reciprocating to rotary and vice versa is
.…………
A. an axle B. an arm C. a crank D. a lever
30 The turning effect of a force about a fulcrum is known as the of the force.…………
A. moment B. product C rotary. D. effect
31 The perpendicular distance between the force’s line of action and its fulcrum are measured.
A. right distance B. left distance C. distance at right
angle
D. distance at left angle
32 Cast iron is a mixture of …………
A. steel and iron B. iron and bronze C. carbon and iron D. steel and carbon
33 The force of attraction exerted by huge mass of the earth is called .…………………
A. natural force B. gravity C. stress D. strain
34 What takes place when austenite transforms into ferrite and cementite?
A. hardening B. quenching C. transformation D. two-step change
35 The value of the constant of each elastic material is called the .………………
A. modulus of elastic B. elastic modulus C. modulus of
elasticity
D. elasticity modulus
36 Compression moulding is a common method thermosets.……………
A. to shape B. for shape C. for shaping D. both A & C
37 Levers .according to the relative positions of the load, the effort and the fulcrum.…………
A. classify B. is classified C. are classified D. classified
38 A force to the roller to keep it in equilibrium.……………
A. must be applied B. must apply C. must applied D. apply
39 Heat treatment as the heating and cooling of metals to alter their properties.…………
A. is defined B. are defined C. define D. defined
40 Alloys made from copper and nickel are ………………
A. corrosion-resistance B. resist corrosion C. corrosion-resistant D. corrosion

41 To manufacture complicated products, we need large sum of money.
A no B little C a lot of D not
42 In order to manufacture at low cost, everything must be taken care of .the real ………………
manufacture.
A after B before C in D of
43 The .is the first step in manufacturing.……………
A. first model B. original concept C. revised model D. none is correct
44 Unless mild steel is painted, it rust.……………
A. will B. won’t C. is D. are
45 If the doors a lift will not operate.……………………
A. aren’t close B. is close C. are close D. isn’t close
46 A machine which is used to grind a material is called a …………………
A. drill B. drilling machine C. grind D. grinding machine
47 Numerical control means control .……………………
A. by maths B. in maths C. in numbers D. by numbers
48 Which medium actually control the motion of numerical control machine tools?
A. electric system B. electronic system C.electromechanical
system
D. mechanical
system
49 What is one of the principle advantages of numerical control?
A. money reduction B. time reduction C. time increase D. money increase
50 Brass is an of copper and zinc.…………………
A. alloy B. avoid C. mixture D. part
2
51 Aluminum, copper and bronze are metals…………
A. iron B. not iron C. ferrous D. non ferrous
52 When using NC machine tools, the amount of human error is greatly………………
A. increased B. decreased C. stay stable D. the same
53 Thermoset is .…………

A. metal B. non-metal C. ferrous D. non-ferrous
54 Thermoplastics and thermosets are .…………………
A. metals B. non metals C. ceramics D. iron
55 Ceramics can not stand high temperature.
A. true B. false C. no information D. x
56 Corrosion is any chemical actions .harm the properties of a metal.………………
A. of which B. that C. who D. this
57 Stainless steel are usually known as metal.………………
A. corrosion-
resistant
B. corrosion-
resistance
C. corrode-resistant D. corrode-
resistance
58 Galvanic corrosion is the same as .corrosion.………………
A. chemical B. electronic C. mechanical D. electric
59 The thin layer of .on the surface of the metal protects them from corrosion.………………
A. aluminum B. chromium C. oxide D. chromium oxide
60 Engineer have to make sure that two .metals are not allowed to touch together.………………
A. similar B. like C. dissimilar D. same
61 When aluminum sheets are riveted with copper rivets, the aluminum near the rivets
will . in damp condition.……………
A. corrode B. corrosion C. corrodes D. not corrode
62 What is the width of the metal plate? It is 3m .……………………
A. wide B. width C. in wide D. at width
63 A diesel engine is an engine which uses ……………
A. oil B. diesel C. diesel oil D. diesel petrol
64 Plastics are available in many form sheets, tubes, robs.…………………
A. such B. such as C. so D. so that
65 Plastics have to atmospheric corrosion.…………

A. resist B. resistant C. resistance D. resistion
66 Thermoplastics will soften when .and harden when……… ………
A. heated/cooled B. cooled/heated C. hot/cool D. cool/hot
67 What happen after the steel has been treated to the austenitic state?
A. take place B. take on C. produce D. deal
68 Heat treatment is the heating and cooling of metals to change their properties.
A. qualities
B. characteristics
C. wealth D. riches
69 To .steel, it must be cooled rapidly after being put into the austenitic condition.………
A. hard B. harder C. more hard D. harden
70 There are two possible ways of indicating the limit permitted for from the stated basic ……………
size.
A. variation B deviation C. accuracy
D. error
71 The design of the measuring tools are very sophisticated.
A. simple B. complex C. easy D. difficult
72 This section will deal with the measuring tools.
A. dear B. work with C. solve D. tell
73 Machinists and tool makers use measuring tools in the everyday performance of their trade.
A. workers B. engineers C. workers working
with machines
D. workers who
produce machines
74 All precision measuring tools must be handle with care in order to avoid damage to them.
A. accuracy
B. similarity C. exactly D. true
75 Which is used primarily to measure the hole diameter?
A. outside caliper B. inside caliper C. hermaphrodite
caliper

D. caliper
3
76 What must the workman depend upon in order to make accurate measurement?
A. sense of feel B. tip of finger C. finger D. skin
77 Which is used to measure the distance between a surface and a scribed line?
A. hermaphrodite
caliper
B. out side caliper C. inside caliper D. telescoping gage
78 Which has two contact plungers?
A. outside caliper B. inside caliper C. telescoping gage D. small hole gage
79 Bilateral tolerance is specified as a or minus deviation from the basic dimension.…
A. add B. include C. plus D. zero
80 The maximum and minimum dimension resulting from the application of the designated tolerance
are called .dimension.……………
A. deviation B. limit C. accuracy D. bilateral
81 Allowance is the intentional, desired difference in of two mating parts.…………
A. dimension B. limit C accuracy. D deviation.
82 In fits, the largest shaft is smaller than the smallest hole.…………
A. interference B. clearance C. inside D. outside
83 In interference fits, the hole is .than the shaft.…………
A. bigger B. taller C larger. D smaller.
84 Workmen use their tip of fingers to decide the .of the tools.……………
A. dimension B. accuracy C. maximum D. minimum
85 The steel bar has a of 3 meters.……………
A. long B. in long C. length D. in length
86 The belt is sixty millimeters .………
A. in wide B. in width C. width D. of wide
87 The electricity pylon is 25 meters…………………
A. height B. high C. in high D. of height
88 What is the of the oil tank?……………

A. deep B. in deep C. in depth D depth.
89 Plastics are used to make a great variety of product textiles engineer……… …
A. such/as B. so/that C. from/of D. from/to
90 Plastics are used widely in engineering they are cheap.……………
A. because B. because of C. so that D. therefore
91 Plastics have resistance to atmospheric corrosion, they are not particularly strong.……
A. because B. because of C. however D. more over
92 Friction is essential in brakes it is a nuisance in an engine,……………
A. so B. however C. because D. therefore
93 Numerical control machine tools are very useful .they are used to machine parts in small ………
and medium quantities.
A. therefore B. because C. but D. however
94 Numerical control machine tools can machine difficult shapes by means of a.
A. robot B. automatic system C. tracer controlled
unit
D. NC controlled
unit
95Mechanism is a component of machine that transmit or change ……………
A. force B. effort C. motion D. movement
96 Parts which have teeth that can engage another wheel with teeth are called……………
A. bearings B. pinions C. jacks D. gears
97 An elastic material that returns to it original shape after being force out of that shape is …………
A. gear B. bearing C. spring D. cam
98 The bearings which contain small round balls and sometimes known as anti-friction
are .………………
A. ball bearings B. roller bearings C. needle bearings D. non-contact
bearings
99 Bearings that touch only at rest, in motion they are separated by gas are called…………
A. ball bearings B. non-contact bearings C. roller bearings D. needle bearings
100 is motion in a straight line and goes back and forth in the same path.…………

A. linear motion B. rotary motion C. translation D. reciprocating
motion
101 An international metric measure of power equal to one joule per second is known as ………
4
A. Watt B. Newton C. Kilowatt D. power
102 There are two main kinds of motion in engineering, they are rotary and .motion.…………
A. linear B. straight C. reciprocating D. circular
103A twisting force that produces torsion or rotary motion is ……………
A. compressive force B. tensile force C. torque D. effort
104 Machines whose input is a natural source of energy are called …………
A. machine tools B. movers C. machinists D. prime movers
105 Force must always occurs in .………………
A. couple B. pair C. two D. twice
106 The resistance to motion when one body is rotating but not on the same axis is……
A. sliding friction B. static friction C. rolling friction D. stop friction
107 In engineering, drilling machines, milling machines and lathes are called .…………
A. numerical controls B. machine tools C. NC machines D. transfer types
108 Which medium actually controls the motions of numerical controlled machine tools?
A. electric system B. electronic system C. electromechanical
system
D. mechanical system
109 Friction is sometimes a help it is a hindrance.……………
A. but B. so C. therefore D. and
110 Oil is used for bearing it is self-lubricating. …………
A. but B. however C. so D. because
111 A wheel with teeth that can engage another wheel with teeth to transmit or change motion is
called . …………
A. bearing B. gearing C. gear D. wheel and axle
112 Friction is the to relative motion of two bodies in contact with each other.……
A. resist B. resistance C. resistant D.resistation

113. Which two factors must be specified in order to obtain the desired fit between mating parts?
A. allowance and
tolerance
B. allowance and
deviation
C. accuracy and
tolerance
D. dimension and
tolerance
114. The undesirable, but necessary and permissible deviation from a desired dimension is
called ……………
A. actual dimension B. tolerance C. limit dimension D. variation
115. There are vector quantities in engineering.…………
A. only three B. many C. not many D. very few
116. Heat treatment is the of metal to change its properties.……………
A. heating B. cooling C. heating and
colding
D. heating and
cooling
117. Tensile forces and compressive forces have effects on bodies.…………………
A. same B. opposite C. different D.some
118. An organic material is a material which is based chemically on …………
A. carbon B. metal C. iron D. carbon dioxide
119. How many kinds of plastics used in engineering?
A. only one B. 2 C. many D. so many
120.What does corrosion specially attack?
A. plastic B. steel C. metal D. All above
121. can be completely corrosion-resistant.………………
A. Alloy B. Metal C. Chromium D. No material
122. In which countries does each view appear in a place appropriate to its name?

A. The US B. France C. Canada D. both A and C
123. The hermaphrodite caliper is used to ………………
A. measure the distance between a surface
and a scribed line
B. to scribe a line from a surface
C. to measure the distance between inside
and outside.
D. both A and B
124. We apply heat treatment primarily on ………………
A. iron B. steel C. wood D. gold
125. Within the elastic limit, If we double the stress on a body we will the strain produced.………
A. double B. triple C. reduce D. keep
5
126. What are the two most important ferrous metals?
A. cast iron and
steel
B. iron and steel C. alloy and steel D. copper and
aluminum
127. Cupronickels have resistance to
A. fresh water B. salt water C. both A and B D. either A or B
128. Chromium can be added into steel to
A. resist corrosion B. increase softness C. increase hardness D. both A and C
129. What may make a body rotate about a point and move in a straight line at the same time?
A. An action B. A force C. A lever D. A jack
130. Levers are used to heavy blocks.
A. move B. carry C. lift D. both A and C
131. How many groups of orders can levers be divided into?
A. only one B. two C. three D. four
132. Levers are classified according to relative positions of .
A. the effort B. the fulcrum C. the load D. All above

133. The wheelbarrow is a lever of
A. the first class B. the second class C.the third class D. none
134. To gain more mechanical advantages, the distance between the point of effort and the fulcrum
can be
A. shortened B. lengthened C. either A or B D. neither A nor B
135. What are three remaining basic machines?
A. the wedge, the inclined plane, the screw B. the wheel, the axe, the screw
C. the wedge, the wheel, the axe D. the inclined plane, the wheel, the axe
136. Numerical machine tools are used to machine .
A. large parts only B. small parts C. medium parts D. both B and C
137. Using numerical machine tools, we can the scrap rate during the manufacturing
process.
A. decrease B. increase C. slow down D. create
138. How many kinds of friction?
A. one B. two C. three D. four
139. What is the modern development in which there is contact between the machine parts only at
rest?
A. bearing B. non- contact
bearing
C. roller bearing D. ball bearing
140. What are machines whose input is a natural source of energy?
A. devices B. prime movers C. motions D turbines
I. dịch việt anh
1Chúng ta có thể chia đòn bẩy thành nhóm theo trật tự xắp xếp giữa trọng tải, điểm tựa và ngoại lực
2.Kim loại có độ tinh khiết cao thờng có độ ăn mòn tốt hơn hợp kim
3.Véc tơ là một đại lợng có độ lớn và có hớng.
4Một vật liệu có tính đàn hồi có thể trở lại hình dáng ban đấu sua khi lực sinh ra biến dạng không còn
5.Sự ăn mòn tấn công tất cả các vật liệu cơ khí đặc biệt là kim loại.
6 Sự chống lại chuyển động tơng đối của các bộ phận chuyển động tiếp xúc với nhau là ma sát.
7Bôi trơn là một cách để giảm ma sát.

8 Có ba loại ma sát cơ học; ma sát tĩnh, trợt và lăn.
9 Ma sát xuất hiện trong tất cả các thiết bị cơ khí.
10 Đòn bẩy là ứng dụng của nguyên lý momen lực tại một điểm.
11 Ma sát là một lực mà ngăn cản chuyển động.
12 Dung sai hai chiều là sai lệch dơng và âm từ kích thớc cơ bản.
13 Hình chiếu đứng là bề mặt đợc mô tả nhiều nhất.
14 Hình chiếu thay đổi theo vị trí của ngời quan sát.
15Một điểm mà tại đó một vật thể có thể tự do xoay quanh gọi là điểm tựa.
6
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Thêi gian : 45’ - §Ò 1.
Name:
Class:
I/ VOCABULARY AND GRAMMAR
1. The intensity of stress depends on___________
A. c.s.a B. size of the
force
C. stress D. Both A and B
2. Most materials used in engineering are__________
A. Plastic B. tough C. elastic D. rigid
3. Distortion due to stress is called___________
A. strain B. stress C. stress and
strain
D. tensile
4. Mild steel is______________ material
A. a plastic B. an elastic C. a tough D. a corrosion
resistance

5. A body which undergoes a tensile force will________
A. shorten B. lengthen C. extended D. expanded
6. ___________materials regain their original shape and size
A. rigid B. elastic C. tough D. plastic
7.Aluminum is _____________metal
A. ferrous B. non ferrous C. non metal D. contain iron
8. Ceramic can withstand_____
A. high
temperature
B. heat C. Both A and B D. all are correct
9. Corrosion attacks ____________
A. ferrous metals B. non-ferrous
metals
C. non metals D. all materials
10. ___________is added to resist corrosion
A. Brass B. Bronze C. chromium D. aluminum
11. Forces must always occurs in ______________
A. couple B. pairs C. two D. twice
12. The force of attraction exerted by huge mass of the earth is called ________
A. Nature force B. gravity C. stress D. strain
13. Cast iron is a mixture of __________
A. steel and iron B. iron and
bronze
C. carbon and
iron
D. steel and
carbon
14. Plastic and ceramics are ________
A. metals B. non-metal C. non – ferrous D. ferrous
15. 1. What does corrosion attack?

A. Plastic B. steel C. chromium D. All A, B, C are correct
16. 3. Which metal can be completely corrosion-resistant?
A. stainless steel B. chromium C. plastic D. None
17. How many percent are heat treatment carried out on steel?
A: 40% B: 50% C:90% D: 95 %
18. What takes place when austenite transforms into ferrite and cementite?
7
A: hardening B: quenching C: transformation D: two-step change
19.Complex means:
A: A. complicated B: B. easy C: C.difficult D: D. different
20. Which are the two most important ferrous metal?
A:steel& iron B:cast iron & steel C:chromium D:alluminium
II/ TRANSLATION
1. Mọi vật liệu đều có thể bị ăn mòn tấn công, ngay cả thép không rỉ cũng vậy
.
2. Dung sai có hai loại: dung sai một chiều và dung sai hai chiều.
.
3. Lực mà cản trở sự chuyển động đợc gọi là ma sát
.
4. Crôm thờng đợc thêm vào thép để chống ăn mòn
.
5. Kim loại tinh khiết thờng có độ kháng ăn mòn tốt hơn hợp kim
.
6. Engineers have to know the best and most economical materials to use. Engineers
must also understand the properties of these materials.
.
.
7. When two different metals touch each other in the presence of moisture, corrosion
occurs. This type of corrosion is known as galvanic or electronic corrosion because it
has an electrical cause.

.
.
8. The measurement while rotating hastens the wear of the measured surface and is
dangerous at the same time.
.
.
9. Do not force the work piece in to the jaws, with a slider being fixed by a set screw.
.
.
10.Friction is essential in brakes. However, it is a nuisance in an engine.
.
.
11.Hình chiếu trong bản vẽ là ảnh của bề mặt vật thể gần ngời quan sát nhất

11.Hình chiếu sẽ biến đổi theo vị trí của ngời quan sát.

12.Hình chiếu cạnh là hình mà ngời quan sát thu đợc khi nhìn vật thể từ góc trái hoặc phải
so với hớng chiếu thẳng.

13.Có hai hệ thống qui ớc; một là hệ thống của hầu hết các nớc châu Âu, một là của các
nớc nh Mỹ, Canada và Anh.


14.Khi đã biết đến cách sắp xếp các hình chiếu, một kỹ s có thể hình dung ra hình ảnh 3
chiều của một vật thể từ bản vẽ của nó.


8
15.Có hai loại dung sai; dung sai một chiều và dung sai hai chiều

16.Dung sai cho phép sai số từ hai phía là dung sai hai chiều.

17.Dung sai một chiều chỉ có một giới hạn đợc hiển thị còn giới hạn kia đợc hiểu ngầm là
bằng 0.

18.Các nhà thiết kế khi làm việc với CAD không cần phải vẽ trên giấy.

19.Với các bản vẽ truyền thống, ta cần phải hình dung hình ảnh 3 chiều của một vật thể
nhng với CAD thì ta không cần.


20.Không nên đo một vật gia công khi đang xoay

21.Không đợc ấn vật gia công vào hàm kẹp và kéo mạnh nó ra nếu nó bị mắc.


22.Sau khi dùng thớc đo xong, không nên rửa sạch nó bằng xà phòng. Nên giũ gìn nó
bằng cách lau bằng một miếng giẻ sạch.


23.Việc dùng thớc đo không cẩn thận sẽ làm hỏng độ chính xác của thớc đo, gây ra mất
tính hữu ích của nó trong việc đo lờng chính xác.



24.Dung sai là sự sai số không mong muốn nhng cần thiết và có thể chấp nhận đợc từ một
kích thớc mong muốn.

25.Hệ thống điều khiển số đã đợc sử dụng trong hầu hết các loại máy công cụ, cũng nh
máy vẽ nháp, máy đột dập, và máy kiểm tra.

26.Một trong những u điểm của điều khiển số là nó cho phép gia công những chi tiết có
hình dạng khó gia công.

27.Có lẽ u điểm chính của điều khiển số là giảm đợc đáng kể thời gian chuẩn bị gia công
và số lợng các bớc để gia công các chi tiết.

28.Điều khiển số còn làm giảm rất nhiều các lỗi do con ngời gây ra.

29.Bất kỳ ai đã nắm đợc những bớc vận hành cơ bản của máy công cụ đều không khó
khăn gì cũng có thể viết ra đợc một chơng trình cho các máy công cụ điều khiển số
thông thờng.

30. Tuy nhiên, việc viết chơng trình cho các máy công cụ điều khiển số phức tạp nhất thì
lại không đơn giản nh vậy

Complete the following sentences.
31.Hundreds/ identical parts/ could/ produced/ machines.
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32.Only/ portion/ the wheels would/ make/one man.

33.A single part/ be/ attached/ each man

34.The early railroad cars/ be / pulled / by horses.

35.The rails/ the early railroad cars/ make/ steel.

36.The assembly line/ introduced/ by Whitney.

37.Standardization/ parts/ also/ introduced/ by him.

38.More than 90% heat treating operation/ carry out/ on steel.

39.To harden steel, it/ must/ cooled/ rapidly enough/ after/ be put/ into / austenitic
condition.

40. Steel/ heat treated/ for/ at least/ hundreds of years.

Task 2
Translation
41.Nhiệt luyện là việc nung nóng và làm nguội kim loại nhằm thay đổi cơ tính của chúng

42.Thép đã đợc nhiệt luyện cách đây hàng trăm năm rồi

43.Gia công nguội có nhiều u điểm vợt trội so với gia công nóng dới góc độ sản xuất hàng
loạt


44.Nếu thép đã đợc nhiệt luyện ở trạng thái austenictic, nó sẽ đợc làm nguội nhanh chóng
bằng cách nhúng vào môi trờng tôi lạnh.


45.Một nhợc điểm của gia công nguội là nó đòi hỏi những máy móc hạng nặng và đắt
tiền. Do vậy nó chỉ phù hợp khi gia công với số lợng sản phẩm lớn.


46.Unless the doors are closed, a lift will not operate

47.Unless mild steel is painted, it will rust.

48.Unless electrical equipment is earthed, it may be electrical leaked

49.Unless proper consideration is given to these matters when a product is in the design
stages, the cost of obtaining the desired surface may easily beome a consideration
portion of the total cost.


50.If a sound understanding of the available methods is combined with the proper design,
the cost of obtaining a satisfactory finish may be greatly reduced
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51.Unless the ignition is switched on, a car can not start.

52.Unless the pilot light is on, gas central heating will not operate.

53.Unless the diverter valve is switched to central heating, the radiators will not radiate

54.Unless there is current flowing in the primary coil of a transformer, there will be no
current in the secondary coil.

55.Unless there is a mixture of petrol and air in the cylinders, a petrol engine will not
start

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