Middle school students _________ smoke because it is bad for their health.
--- When will the popular film star arrive here?--- I don’t know when he _________. When he _________here, I’ll call you in a minute.
—Were you at Mary’s party last night?—No, I ____________ my sister. She met with difficult problems.
My grandparents____ in that city since 2008.
一Oh,there’s someone knocking at the door. 一 must be that naughty boy.
We can’t do it that way --- but whether it will work is ______ matter.