20．When people want to know about the weather，they usually go to there radios，TVs，newspapers，or to the Internet．However，you can also find many weather signs among wildlife，because of their highly developed senses．Drops in air pressure（压力） produce an effect on small animals in many ways．Mice and deer are good weather indicators．People who spend a lot of time outdoors have observed that，before a storm，field mice come out of their holes and run around，Deer leave high ground and come down from the mountains．
Birds are especially good weather indicators because they also show the effect of a pressure drop in many ways．For example，some birds become irritable（急躁的）and quarrelsome and will fight over a price of bread．Other birds chirp（叽叽喳喳）and sing just before a storm．It seems they know they won't get another chance for an hour on two．Birds also seek safe places before a storm，You will sometimes see birds settling in trees or gathering together on a wire close to a building．Pre-storm low pressure makes the are so thin that birds have difficulty flying．
It is unusual to see many birds flying overhead in the summertime，rather than during the periods in the spring or autumn．Watch for other weather signs if you see this．If they fly in the wrong direction，they may be flying ahead of a storm．
By paying closer attention to some important signs in nature，we can become better prepared for any kind of weather．
32．The word"indicators"in paragraph I probably meansC．
A．maps B．services
C．signs D．stations
33．There will be a storm if birdsA．
A．make more noise than usual
B．fly in different directions
C．come down from tall trees
D．share a piece of bread
34．How can birds sense the coming of a storm？C
A．By feeling a drop in air temperature．
B．By noticing the change of wind directions．
C．By feeling a drop in air pressure．
D．By noticing the movements of other animals．
35．The best title for the text would beD．
A．Signs of a Storm
B．Drops in Air Pressure
C．Animals'Sharp Senses
D．Nature's Weather Signs．
