When you ______ a difficult task, try to continue with it and finish it.

I didn’t know your mobile phone number; otherwise I____ you the second I got to Changsha.[ ]

You _____ have come to the meeting. There were so many famous people and the argumentation among them was so excellent.

mputer center, ________ last year, is very popular among the students in this school.

Could you please tell me something about the two____— ____. They arc exchange students of No. 1 Middle School.