单项选择题
A. The room service is always unavailable when it is needed. B. The charges on directly dialed calls are not reasonable. C. It is about a delay in the switchboard. D. Something is wrong with his telephone.
A. sleep longer than humans B. have similar sleeping habits as humans C. have no regular sleep D. take naps in addition to their regular sleep
A. 19 B. 20 C. 21 D. 22