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  3. Why, you may wonder, should spiders be our friends? Because they protect so

Why, you may wonder, should spiders be our friends? Because they protect so

游客2024-12-27  21
问题     Why, you may wonder, should spiders be our friends?
Because they protect so many insects,and insects include 【M1】______
some of the greatest enemies of the human race. Insects
would make impossible for us to live in the world; they  【M2】______
would ruin all our crops and kill our flocks and herds,
as it were not for the protection we get from insect     【M3】______
- eating animals. We owe a lot for the birds and beasts  【M4】______
who eat insects but all of them put together kill only
a fraction of the amount destroyed by spiders. Moreover, 【M5】______
unlike some of the insect - eaters, spiders never make   【M6】______
the least harm to us or our belongings.
    Spiders are not insects, as many people think, and   【M7】______
nor even nearly related to them. One can tell the difference
almost at a glance, for a spider always has eight
legs but an insect never more than six.
    How many spiders are joined in this work on our      【M8】______
behalf? One authority on spiders made a census
of the spiders in a grass field in the south of
England, and he estimated that there were more
than 2,250,000 in one acre; that is anything             【M9】______
like 6,000,000 spiders of different kinds on
a football pitch. Spiders are busy least
half the year in killing insects. It has been
estimated that the weight of all the insects
destroyed by spiders in Britain in one year would
be greater than those of all the human beings           【M10】______
in the country. [br] 【M3】
选项
答案 as: if
解析 根据上下文，这里应该是个似设关系，意为“我们如果没有了食有害昆虫动物的保护的话，昆虫便会毁了我们的庄稼和牲畜。”所以这里用if才符合原文之意。
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