题干

“锄禾日当午”中的“锄禾”即为疏松土壤,其生物学的意义是(  )

A:破坏土壤中蝼蛄等害虫的生活环境

B:减轻土壤板结对农作物根系向下生长的限制,以便植物吸取地下水

C:改善土壤中蚯蚓等有益动物的生活环境

D:增加土壤透气性,有利于农作物根系的呼吸作用和对无机盐的吸收

上一题 下一题 0.0难度 选择题 更新时间:2018-04-24 03:49:26

答案(点此获取答案解析)

D

同类题2

Good evening, ladies and gentlemen. Welcome to the nine o’clock Mystery Hour. Today we’ll show you two British stories. We hope you’ll enjoy them.
About 900 years ago two green children arrived in a small village in south England. Their eyes and skin were green and they spoke a strange language. They were very tired and weak, so the people of the village looked after them. The boy died a year later, but the girl grew strong and lived the rest of her life there. And her skin colour turned back to normal day by day. Scientists say that sometimes of people don’t have enough food to eat for a long time, their skin goes very pale and can even turn green.
Loch Ness is the largest lake in Scotland. It’s a very deep and cold lake. For hundreds of years, people have talked about a monster(怪物) called Nessie which lives in the lake. About seventy years ago, two people saw something moving in the lake. They said that the animal was playing and rolling around in the water. Since then many people say they have seen the monster. Their descriptions are always the same. It looks like a dinosaur, with a very long neck and a small head. It has a big bump(包,肿块)on its back. People have tried to photograph the animal, but the pictures have not been very clear. Scientists don’t know whether there is a monster or not. Some say it may be a whale or a very large fish. Some think it’s a snake. Others say there’s nothing at all— nothing but people’s imagination. Maybe we’ll never know what’s in Loch Ness.