The old rules have to be_____because they only applied to the circumstances that existed when they were made a hundred years ago.

We ________ used computers years ago, but now they are everywhere.

Tom, would you like to stop practising B-Box The CCTVnews____ and I want to listen.

Not until _____the exam _____ the importance of doing homework.

Students should involve themselves in community activities ___________ they can gain experience for growth.