单项选择题

According to some scientists' research findings, dolphins seldom sleep because ______.

A．of their stupidity
B．of their vulnerability
C．there are possible dangers in the ocean
D．aquatic mammals do not need sleep
<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
Which of the following might be the best title for this passage
A．Evolution of Sleep.
B．Two Types of Sleep.
C．The Original Function of Sleep.
D．Animals and Sleep.
相关试题