必须脂肪酸_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题名词解释

必须脂肪酸

答案

参考答案：

自然界存在的脂肪酸有40多种，有几种脂肪酸自身不能合成，必须有食物供给，称为必须脂肪酸。

完形填空

The world is divided into two parts. One half of the world is rich and   26  is poor. In the poor part, a lot of people have 27 got enough to eat. When they are ill, none of the   28 can receive them because they have no money. In the rich   29 , people eat very well,   30 a dog or a cat in North America eats   31 than a child in poorer countries.
The poor countries have some difficult problems. Sometimes the land is too poor to grow 32 on. People there have   33 rich land nor enough water. The land   34 be made better, but a lot of things must be done. The people must be taught and water must   35 .
But rich countries have problems, too. There are not always good places to   36 . Sometimes the air is not clean and the rivers are too   37 to swim in or to drink. The roads and streets are full of people and cars. Cars and buses have to move   38 . Noise is too much. Some people have no houses to live in. Something must be done about these problems. The air and the rivers must be cleaned and be   39 clean. More houses have to be built.   40 these things cannot be done easily.

填空题

汽车排放污染主要来源于（）。