30Because of the heavy snow, a serious accident______to the family

_______ have fought with the policeman.—Yes. If one ________ ask for trouble, it can’t be helped.

We should________the lights when we leave our classroom because we mustsave electricity.[ ]

The computer, help we human beings have stepped into the information age, should be regarded as one of the most important inventions in the 20th century.

Excuse me, visiting hours are over．It’ s time for you to leave．—I’ m sorry, I didn’t know the time or I ______ earlier．