21、— When did you last see your first teacher?

— On _______ Friday last June, at _______ celebration of her 40^th year of teaching．

A．a; the          B．a; a          C．不填; the          D．不填; a

20、We went into a hall, on _______ walls hung a few pictures of some famous scientists．

A．its          B．which          C．whose         D．those

19、— Hello, everyone! Have you heard the meeting will be put off?

— Yeah, that’s what we _______ about when you came in．

A．were talking              B．are talking            C．have talked            D．had talked

18、Life insurance is not really betting although it can be compared to it．You pay the money just _______．

A．in time          B．in case          C．in return         D．in honor

17、You will be at a（n） _______ if you have thought about the interview questions in advance in application for a job．

A．favor           B．advantage          C．benefit          D．profit

16、The boy was busy doing his homework, only _______ once in a while to look out of the window．

A．stopping        B．to stop            C．stopped          D．having stopped

15、You can’t complain of being lonely _______ you don’t make any effort to communicate with others．

A．when        B．until          C．unless        D．once

14、The moment we heard of the accident, we _______ the work to rescue those trapped in the mine．

A．set off          B．set down         C．set back               D．set about