1．can，could，may，might，must (包含其否定形式)
①Helen__________go on a trip with us，but she isn't quite sure.
②Peter__________be really difficult to get along with at times even though he's a nice person in general.
③My sister met him at the theatre last night，so he__________have attended your lecture.
④If you__________go，at least wait until the storm is over.
⑤—Might I use your car?
—Yes，of course you__________．
⑥—May I turn up the TV a little?
—Sorry，you__________．You will wake the baby.
⑦—Could I borrow your bike?
—Yes.Of course you__________．
⑧—Must I hand in this paper one hour later?
—Yes，you__________．
⑨—Is John coming by bus?
—He should，but he__________．He likes riding his bike.
⑩—Isn't that your teacher over there?
—No，it__________be him.I'm sure he doesn't wear glasses.
