题目内容
阅读下列短文, 从所给的四个选项中, 选出最佳答案。
Bats are the only flying mammals(哺乳动物)in the world. They can't see very well, but they have no trouble flying on the darkest nights and catching the insects (昆虫) that they eat. How do bats manage to fly by radar (雷达)? The bats' radar system (系统) works the same way as the one the ships and planes use, like the radio signals that bounce (反射) back when they hit an object. As a bat flies through the air, he sends out of series (系列) of sounds, thirty to sixty per second. The sound can't be heard by the human ear. If the sounds hit an object, these returned sound signals tell the bat where the object is. The bats' radar system is very good.Tests have been made with bats in a crowded room. Blind in the light, the bats could fly about the room and never touch any object.
(1) This article tells us how _________.
[ ]
A. radar system works
B. bats sent out sound signals
C. sound signals bounce back
D. bats manage to fly and see at night
(2) Bats have no trouble flying on the darkest night because_________.
[ ]
A. they have very poor sight
B. they can catch insects to eat
C. they have a kind of radar system to help them
D. they can see objects in the dark night
(3) As bats fly through the air,_____________.
[ ]
A. they send loud radio signals
B. they hear all kinds of sounds
C. they hit objects and bounce back
D. they send out sound signals
(4) The bat's ears pick up the sounds. This means__________.
[ ]
A. the bat can hear the returned sound signals
B. the bat is unable to hear the sound signals
C. sound signals become stronger when they bounce back
D. sound signals get lost when they bounce back
(5) The bats are completely blind __________.
[ ]
A. in the darkness B. in the light
C. in a crowded room D. at night
