My deskmate is still a puzzle to me; at one moment he is quiet while at another he _____ be quite active.
Was it an accident or did David do it ________?
Do you know any other foreign language ________ French?
We had to stay at home ________ a heavy rain.
You’d better have your bike ________, or it’ll get you into trouble.
--- Do you know our city at all? --- No, this is the first time I ________ here.