Bats are the only mammals(哺乳动物) which can fly properly. Other flying mammals have wings of thin skin which cover their sides between their front and back legs. They can only fly from tree to tree, but they cannot change direction when they want to.
All bats fly at night and most of them hunt for flying insects(昆虫), such as bees. The common bat finds its food by
making a constant noise that the human ear cannot 
hear. The bat listens for echoes(回声) of the noise as it bounces(反射) off the insects showing the bat their position.
The Fruit bat feeds on many different kinds of fruit. It does not use echoes but instead has very large, special eyes to see even in low light. The largest Fruit bat has a wing length of 0.75 meters. The Vampire bat drinks the blood of large mammals, and a few bats catch fish, birds and even other bats.
小题1: Some flying mammals are not real flyers because _____.
A．they do not have wings
B．their wings are too thin
C．they have skin between their legs
D．they cannot turn around in the air小题2: When common bats hunt for food they _____.
A．use echoes to kill the insects
B．make a noise to draw insects to them
C．produce a sound and listen to the echoes
D．listen noise made by the insects小题3: Unlike other bats, the Fruit bat _____.
A．can see very well
B．eats fruit and fish
C．has very long wi
ngs
D．has excellent hearings小题4:The word "it" in the second paragraph refers to ____
_.
A．the bat
B．the echo
C．the noise
D．the insect
图中①、②分别表示以下哪两种设备