Why, you may wonder, should spiders be our friends? Because they destroy so many insects, and insects including some of the greatest enemies of the human race. Insects would make it impossible for us to live in the world; they would devour（吞食、毁灭）all our crops and kill our cattle, if it were not for the protection we get from insect-eating animals. We owe a lot to the birds and beats who eat insects, but all of them put together kill only a very small amount of the number destroyed by spiders. Moreover, unlike some of the insect eaters, spiders never do the least harm to us or our belongings.

　　Spiders are not insects, as many people think, nor even nearly related to them. One can tell the difference almost at a glance for a spider always has eight legs and an insect never more than six.

　　How many spiders are engaged in the work on our behalf? One authority on spiders made a research of the spiders and found that there were more than 2250000 in one acre; that is something like 6000000 spiders of different kinds on a football field. Spiders are busy for at least half the year in killing insects. It is impossible to make more than the wildest guess at how many they kill, but they are hungry creatures, not content with only three meals a day. It has been estimated that the weight of all the insects destroyed by the spiders in Britain in one year would be greater than the total weight of all human beings in the country.

(1)Spiders should be our friends, because ________.

[　　]

A．they only eat harmful insects

B．they are great insect-eating animals

C．they destroy large numbers of insects which do harm to the human race

D．their harmfulness is the least

(2)The difference between spiders and insects is that ________.

[　　]

A．insects have only six legs

B．insects only eat plants

C．spiders eat insects

D．spiders have more legs than insects

(3)One authority on spiders estimated ________.

[　　]

A．that there were more than 2250000 insects in a grass field in the south of England

B．that every football field in England had 6000000 spiders

C．the quantity of different spiders in England was very big

D．that there were 6000000 kinds of spiders on a football field

(4)In the last sentence the writer means ________.

[　　]

A．experts on spiders know exactly how much spi ders eat in one year

B．experts on spiders can only make an estimation of the weight of insects eaten by spiders

C．authority on spiders know the weight of all the people in England

D．authority on spiders know both the weight of the insects eaten by spiders and the weight of people in England

　　Why, you may wonder, should spiders be our friends? Because they destroy so many insects, and insects including some of the greatest enemies of the human race. Insects would make it impossible for us to live in the world; they would devour（吞食、毁灭）all our crops and kill our cattle, if it were not for the protection we get from insect-eating animals. We owe a lot to the birds and beats who eat insects, but all of them put together kill only a very small amount of the number destroyed by spiders. Moreover, unlike some of the insect eaters, spiders never do the least harm to us or our belongings.

　　Spiders are not insects, as many people think, nor even nearly related to them. One can tell the difference almost at a glance for a spider always has eight legs and an insect never more than six.

　　How many spiders are engaged in the work on our behalf? One authority on spiders made a research of the spiders and found that there were more than 2250000 in one acre; that is something like 6000000 spiders of different kinds on a football field. Spiders are busy for at least half the year in killing insects. It is impossible to make more than the wildest guess at how many they kill, but they are hungry creatures, not content with only three meals a day. It has been estimated that the weight of all the insects destroyed by the spiders in Britain in one year would be greater than the total weight of all human beings in the country.

(1)Spiders should be our friends, because ________.

[　　]

A．they only eat harmful insects

B．they are great insect-eating animals

C．they destroy large numbers of insects which do harm to the human race

D．their harmfulness is the least

(2)The difference between spiders and insects is that ________.

[　　]

A．insects have only six legs

B．insects only eat plants

C．spiders eat insects

D．spiders have more legs than insects

(3)One authority on spiders estimated ________.

[　　]

A．that there were more than 2250000 insects in a grass field in the south of England

B．that every football field in England had 6000000 spiders

C．the quantity of different spiders in England was very big

D．that there were 6000000 kinds of spiders on a football field

(4)In the last sentence the writer means ________.

[　　]

A．experts on spiders know exactly how much spi ders eat in one year

B．experts on spiders can only make an estimation of the weight of insects eaten by spiders

C．authority on spiders know the weight of all the people in England

D．authority on spiders know both the weight of the insects eaten by spiders and the weight of people in England