What is soil? It is the skin of the Earth. It supports all forms of our life. Nearly all our food comes from the soil. Some of us eat meat, some eat vegetables, but most animals live on plants. If there are no plants, we will have no vegetables, no animals and no meat.
Plants grow in soil with a dark colour. The dark soil is humus (腐殖土壤). Dead leaves, dead plants and animals’ waste make it, but it takes a long time. When the humus has been made, plants can grow well in it.
All soil needs food. Animals’ waste is the best food for the soil, but chemical fertilizers (化肥) are also very useful. The same crops should not be grown in the same place every year. A change of crops 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, so we must save every bit of it. Without soil, how can we live?
31. From the first paragraph, we can know ________.
A.all animals eat plants | B.most animals eat meat |
C.all our food comes from plants | D.people, animals and plants all live on soil |
32. Which is the best food for soil?
A.Animals’ waste. | B.Dead plants. | C.Dead leaves. | D.Chemical fertilizers. |
33. To keep the land in good condition, we should ________.
a. grow the same crops in the same place
b. grow different crops in the same place
c. use a good fertilizer
d. never use a fertilizer
A.a & c | B.b & c | C.a & d | D.b & d |
34. Which of the following is NOT true?
A.Soil is the skin of the Earth. | B.Humus helps plants grow well. |
C.It takes a hundred years to make humus. | D.Growing trees and plants can help keep the soil. |
35. Which of the following is the best title?
A.Plants and animals | B.Soil and waste | C.Soil and food | D.Humans and food |