While sleeping, some water mammals tend to keep half awake in order to ________.
A) alert themselves to the approaching enemy
B) emerge from water now and then to breathe
C) be sensitive to the ever changing environment
D) avoid being swept away by rapid currents
The author advises at the end of the passage that ________.
A) overtraining syndrome should be treated as a serious illness
B) overtraining syndrome should be prevented before it occurs
C) an athlete with overtraining syndrome should take a lengthy rest
D) illness causing fatigue should not be mistaken for overtraining syndrome
From the passage we know that the development of high technology is in the interests of ________.
A) the rich countries
B) scientific development
C) the elite
D) the world economy
