Most whales must come up for air after several minutes a few can stay under water for an

问题补充：

Most whales must come up for air after several minutes, a few can stay under water for an hour or more.

A. while

B. or

C. for

D. so

答案：

(答案→)A. while

B. or

C. for

D. so

解析：考查连词;A. while 当…时候，虽然，然而，B. or否则，C. for因为，D. so 因此，句意是;大多数鲸鱼几分钟后要浮出水面呼吸，但还有些可以在水下呆一个小时或更多。选Ａ。