单项选择题

According to this passage, deep dream sleep is more likely to occur in ______.

A．flies
B．vulnerable birds
C．puppies
D．tigers
<上一题 目录 下一题>
热门 试题

单项选择题
The example of dogs and cats in the second paragraph is intended to______.
A．explain which animals are mammals
B．show the differences between mammals
C．illustrate how shallow dreamless sleep is
D．reveal how smart they are
单项选择题
It is because of ______ that dolphins seldom sleep according to some scientists' research findings.
A．their stupidity
B．their vulnerability
C．the possible dangers in the ocean
D．their small size
相关试题