19．Can dolphins talk？May be they can't talk with words，but they talk with sounds．They show their feelings with sounds．
Dolphins talk to the other dolphins in the school．They give information．They tell when they are happy or sad or afraid．They say"welcome"when a dolphin comes back to the school．They talk when they play．
They make a few sounds above water．They make many more sounds under water．People cannot hear these sounds because they are very，very high．Scientists make tapes of the sounds and study them．
Sometimes people catch a dolphin for a large aquarium （水族馆）．People can watch the dolphins in a show．Dolphins don't like to be away from their school in an aquarium．They are sad and lonely．
There are many stories about dolphins．They help people．Sometimes they save somebody's life．People don't like to kill them，because they say that dolphins bring good luck．Many people believe this．
51．Dolphins show their feelings withD．
A．picture
B．words
C．water
D．sounds
52．People can't hear the dolphins becauseC．
A．they are above the water
B．they are under the water
C．they are very high
D．they are very low
53．Which one is TRUE according to the passage？B
A．Dolphins swim together in a school because they want to study．
B．They don't study but they travel in a group．
C．Dolphins like to be away from their school on an island．
D．Dolphins like to kill people．
54．People don't like to kill the dolphins becauseD．
A．they help people
B．their meat doesn't taste good
C．they sometimes save people
D．people believe dolphins are the symbols of good luck
55．What does the underlined word"school"mean？D
A．学校
B．教学
C．学习
D．一群．
