Before you left, please _____ all the windows are closed.A.sureB.make sureC.certainD.as

Please excuse me if I have left any of my questions ______A．to be unansweredB．not to answe

He ordered that everything ______ kept in its original form. before his aunt left.A．would

Please make sure the regulations about how to______the Customs before you choose the chann

Please _____ your food slowly before _____ it.A. swallow ／ chewingB. chewing ／ swal

All the lights ______ before we left the office.A.has been turned offB.have turned offC.ha

Rather ________ by the party he left half an hour before it was ended.