It's suggested that some activities ________ to celebrate the 30th anniversary of the Reform and Opening up.
Young students are ______ not to smoke both in and out school.
He commanded that all the gates _____when it was getting dark in case thieves came in .
Mr. Black has been teaching English in a middle school _____ he came to China.
. — What's that noise?—Oh , I forgot to tell you. The new machine ________
—Sorry. I didn’t break the plate______.—It’s OK. Don’t worry about it.