I tried phoning her office, but I couldn't ______.

单项选择题—How about your trip to Hainan — It couldn't have been ______. Sometimes I went swimming in the sea; sometimes I lay on the sand.

单项选择题—We've spent too much money recently. —Well, it isn't surprising. Our friends and relatives（）around all the time.

A. are coming
B. had come
C. were coming
D. have been coming

单项选择题（）from the top of the tower, the south foot of the mountain is a sea of trees.

A. Seen
B. Seeing
C. Having seen
D. To see

单项选择题—Excuse me, where is the nearest bookshop, please —Sorry, I don't know. —______.

单项选择题Duty is an act or a course of action that people（）you to take by social customs, law or religion.

A. persuade
B. request
C. instruct
D. expect