Cac bai doc hieu TA rat hay

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<b>Why is the sea salty?</b>

There is a lot of salt on the earth, and it mixes very well with water.

There is some salt in all water. Water on the land runs into lakes and rivers. The water
from most lakes goes into rivers. These rivers run into the seas and oceans. They carry a
little salt with them. Some of the ocean water moves into the air and clouds. It

evaporates. Salt cannot evaporate. It stays in the ocean.

The water in the oceans has more salt in than river water. Ocean water is about 3 ½%
(three and a half percent) salt. Some seas have more salt than others.

Some lakes do not have a river to carry the water and salt away. Some of the water leaves
the lakes. It evaporates, but salt cannot. These lakes are very salty. There are two famous
lakes like this. They are the Dead Sea in the Middle East and the Great Salt Lake in the
state of Utah in the United States. There are much saltier than the Atlantic Ocean and the
Pacific Ocean.

<i>Vocabulary: </i>

Evaporate (v): bốc hơi
The Dead Sea biển chết

The Middle East: vùng Trung đông

<b>Questions:</b>

1. What does salt mix well with?
2. Is there salt in lakes and rivers?
3. Where does river water go?

4. Why are some lakes very salty?
5. Name two famous salty lakes.
6* Are there fish in the Dead Sea?

<b>How can a plant kill?</b>

People kill. Animals kill. Animals and people kill for food, or they kill their enemies.
People and animals can move around and find something to kill. They can run away
from an enemy. They can kill it if it is necessary.

Many kinds of animals eat plants. The plants cannot run away from their enemies.
Some plants make poison. If an animal eats part of the plant, it gets sick or dies.
Animals learn to stay away from these plants. There are many kinds of plants that
make poison. Most of them grow in the desert or in the tropics.

Today farmers use many kinds of poison on their farms. Most of these poisons come
from petroleum, but petroleum is expensive. Scientists collect poisonous plants and
study them. Maybe farmers can use cheap poison from plants instead of expensive
poison from petroleum.

<i>Vocabulary:</i>

Enemy (n): kẻ thù
Poison (n): chất độc
Tropics : vùng nhiệt đới
Petroleum (n): dầu mỏ

<b>Questions:</b>

1. Why do people and animals kill?

2. What do some plants make?

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5. Where do most poisons come from?
6* Why do farmers use poison on their farms?

<b>Rice</b>

People all over the world eat rice. Millions of people in Asia, Africa, and South America
eat it every day of their lives. Some people eat almost nothing but rice.

Rice is a kind of grass. There are more than seven thousand (7,000) kinds of rice. Most
kinds are water plants. Farmers grow rice in many countries, even in the southern part of
the United States and in eastern Australia.

No one really knows where rice came from. Some scientists think it started to grow in
two places. They think that one kind of rice grew in southern Asia thousands of years
ago. Someone in China wrote about it almost five thousands (5,000) years ago. Another
kind probably grew in West Africa. Other scientists think rice came from India, and
Indian travelers took it to other parts of the world.

There are two main ways to grow rice. Upland rice grows in dry soil. Most rice grows in
wet soil. People in many countries do all of the work by hand. This is the same way
farmers worked hundreds of years ago. Some countries now use machines on their rice
farms. The farmers all use fertilizer. Some insects are enemies of rice. Farmers poison
them.

People use every part of the rice plant. They make animal feed and rice oil from it. They
also make baskets, brooms, rugs, sandals, and roofs for their houses. They burn dry rice
plants for cooking.

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