Jim, who taught ________Chinese before you came to school?—Nobody. I learned it by _______.

About two _________boys took part in the running race.

All passengers______go through safety check before they take a plane.

Are you_____ now, Dave? I’m visiting you. —Sorry, I’m_____ vacation with my mother.[ ]

Peter dosen’t tell me when he _______ , I will tell you as soon as he ________.