Why would an animal kill itself? It seems a strange question, and yet it is one

Why would an animal kill itself? It seems a strangequestion, and yet it is one that has made some scientists curious for a longtime. For there is a kind of animal called lemming（旅鼠）, that periodically killed themselves together, and noone knows just why!

The small creatures which live in the Scandinavianmountains, feed on a diet of roots and special insects and live in nests theydig underground. When their food supply is large, the lemmings live a normaland undisturbed life. 

However, when the lemmings’ food supply becomes toolow to support the population, a singular migration（迁徙）begins. The lemmings leave their nests in groups.Great numbers of them begin to travel across the Scandinavian plains, a journeythat may last weeks. The lemmings eat everything in their path, continuingtheir long march until they reach the sea. 

The reason for what follows remains unbelievable tonaturalists. Upon reaching the coast, the lemmings do not stop but swim by thethousands into the sea. Most stay afloat only a short time before they tire, sinkand drown. 

A common theory for this mass self-killing is that thelemmings do not realize that the ocean is such a huge body of water in theircross-country journey, the animals must cross many smaller bodies of water, suchas rivers and small lakes. They may think that the sea is just another suchswimmable path to go through. But no final answer has been found to the strangehappening. 

1.The passage is mainly about______. 

A. how lemmings find food

B. why animals kill themselves

C. the lemmings’ self-killing

D. the food supply in the Scandinavian mountains

2.A reason for the lemmings’ self-killing might bethat they______. 

A. go mad from a lack of food

B. hope to find fish for food

C. decide to reduce the population

D. think they can cross the sea

3.Why are scientists curious about the lemmings’behavior?

A. Because they are the only animals that live inScandinavia.

B. Because it is very unusual for animals to killthemselves.

C. Because of the amount of food they can eat on theirmarch to the sea.

D. Because they can gather together in such hugenumbers.

4.The underlined word “singular” means______.

A. unusual       B.single       C. wonderful      D.common

试题答案

【答案】

1.C

2.D

3.B

4.A

【解析】

试题