2.A coral island looks like __________.

　A. a round cake B. trees, grass and flowers

　C. a ring of land D. a round lake

1.In the sea ________.

　A. there are coral islands in all places B. there are some coral islands

　C. the water is always warm D. we can see many flowers

5.The best title of this text should be ______.

　A.Soil is necessary to people

　B.The same crop can’t be grown in the same place every year

　C.Soil’s food is chemical fertilizers

　D.Humus is hard to make

　Passage 5

　In the sea there are many islands. In its warm waters there are some little ones. We call them “coral Islands”.

　A coral island is very nice to look at. It looks like a ring of land (一圈陆地) with trees, grass, and flowers on it. One part of the ring is open to the water. There is a little round lake inside the island.

　If you look into this lake, you will see beautiful coral. You say think they are flowers. If you look at a piece of coral, you will see many little holes in it. In each of these holes a very small sea animal has lived. These sea animals make the coral.

　They began to build under the water. Year after year, the coral grew higher and higher. At last it grew out of the water.

　Then the sea brought it small trees and something else. After some years, these things changed into earth. Sometimes the wind brought seeds (种子) to this earth. Sometimes birds flew over it and brought seeds to the island.

　The little seeds grew. In a few years there were plants all over the island. In a few more years there were trees growing there.

　So you see, these islands were built little by little. The workers were very small. Do they not teach us a lesson? Can you think what the lesson is?

4.We should save every bit of humus, because ______.

　A.it takes a long time to make humus

　B.the more humus in the soil, the better plants grow

　C.the chemical fertilizers are expensive

　D.A and B

3.We should _______ to keep the soil.

　A. give more fertilizers B. kill more animals

　C. make more humus D. grow more trees and grass

2.The word “humus” means _____ in Chinese.

　A.微生物 B.土壤 C.腐殖土 D.粘土

1.From the text, we know people live on _______.

　A. animal B. plant C. meat D. soil

5.The people had to leave the place in New Mexico because _______.

　A.had weather stopped the growth of trees

　B.they no longer had water and the land became sand

　C.they didn’t have enough trees for burning

　D.there was too much rain there

　Passage 4

　All our food comes from the soil (土壤). Some of us eat meat, but animals live on plants. If these were no plants, we should have no animals and meat. So the soil is necessary for life.

　The top of ground is usually covered with grass or other plants. Plants grow in soil, which has a dark color. This dark soil is humus, dead leaves, dead plants and animal waste make it, but this takes a long time. When the humus has been made, plants can grow well in it.

　All soil needs food. If we don’t give it any, the plants will be weak. Animals waste is the best food for the soil, but chemical fertilizers (化肥) are also very useful. The same crop should not be grown in the same place every year; it is better to have a different crop. A change of crop and the use of a good fertilizer will keep the land in good condition.

　When the soil is dry, the wind blows it away. Sometimes heavy rain carries the humus down to a river. People should grow more and more trees and grass to stop wind from carrying the humus away. It takes hundreds of years to make humus, and so we must save every bit of it. Without soil, where can we grow food?

4.Why did people usually live in places with lots of trees?

　A.Trees could tell the change of the weather

　B.Trees brought lots of sunshine and rain

　C.Trees could make weather not too hot or too cold

　D.Trees could be used for burning and for building house

3.If you want to find out the weather of twenty years ago, you should study _______.

　A. the twentieth ring 　　　　B. the tenth ring

　C. the nineteenth ring 　　　D. the twenty-first ring