A、They only get moisture from rainfall. B、They need more moisture than trees elsewhere. C、They can live a long life without wate

admin2016-06-02  33

问题  
(17)Some trees can survive a long time without water. Think of trees that grow in the desert. But other trees may need more moisture than they can get from rainfall or from the air. The soil stores moisture during cooler weather. But most of that moisture is gone by the middle or end of the hottest months of the year.(18)Trees and other plants can look thirsty. Leaves hang downward and turn brown or yellow. Here are some suggestions for watering newly planted trees and established trees. With a newly planted tree, the roots have not yet spread out from the root ball. The root ball can become dry faster than the dirt around it. So put water on the area of the football and the surrounding soil until the roots become established.(19)Once a tree is well established, water deeply instead of often. During the hottest season, a deep watering may satisfy a tree for anywhere from ten days to two weeks.(20)One of the effective watering skills is to stop when the soil needs a little time to absorb the water. Otherwise the water runs off the surface and gets wasted.
17. What can we learn about trees in the desert?
18. What’s the symptom when trees look thirsty?
19. How should we water a tree after it has grown up?
20. Why should we stop watering when the soil absorbs the water?

选项 A、They only get moisture from rainfall.
B、They need more moisture than trees elsewhere.
C、They can live a long life without water.
D、They do not need water to ensure their growth.

答案C

解析 短文开篇便提到,一些树木在没有水的情况下也可以生存很长时间,在沙漠中生长的树木就是这样。
转载请注明原文地址:https://kaotiyun.com/show/3W5K777K
0

相关试题推荐
最新回复(0)