聽短文，根據(jù)短文的內(nèi)容選擇正確的答案。
（1）Dolphins live in

.
A.oceans
B.rivers
C.both A and B
（2）Dolphins are mammals （哺乳動物） because dolphin mothers

.
A.cannot keep their body warm
B.lay eggs
C.make milk for their babies
（3）Dolphins usually swim

.
A.alone
B.in groups
C.slowly
（4）There are

kinds of dolphins.
A.fourteen
B.forty
C.thirty
（5）Dolphins use

to find food and talk.
A.sound
B.teeth
C.mouth