1．So far Peter ____________(not call) back. Shall we make a phone call to him again?
答案：hasn’t called
2．The boss ____________(stay) in New York for four days last week. Now he is working in China.
答案：stayed
3．It is the third time that you ____________(come) to our school.
答案：have come
4．Henry feels rather tired because he ____________(work) in the field for six hours.
答案：has been working
5．She ought to stop working；she has a headache because she ____________(read) all day long.
答案：has been reading
6．The unemployment rate in this district ____________(fall) from 6% to 5% in the past two years.
答案：has fallen
7．Here he is! We ____________(wait) anxiously for him since last night.
答案：have been waiting
8．Up to now, the gifted child ____________(win) three national prizes in music.
答案：has won
9．I ____________(look) for my lost book for three days，but I still haven’t found it.
答案：have been looking
10．The telephone ____________(ring) for minutes, but no one ____________(answer) it.
答案：has been ringing；has answered
