Remember this, children. ________ you study, ________ knowledge you will get.—We know, Mr. Green.

After half a day’s hard work, we made our classroom look as _______ as new.

I don’t know _____she is. –Mrs Smith says she is a shop assistant.

Last summer I took a course on _______ poisonous gases.

Listen! David is talking happily with his mother in the next room.　— It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.