Children under 12 years of age in that country ________ be under adult supervision when in a public library.
A. must B. may C. can D. need
He paid for a seat, when he ______ have entered free.
A. could B. would C. must D. need
Lisa hasn’t lived here for long. She ____ know many people.
A. needn’t B. can’t C. shouldn’t D. didn’t
–Who is the girl standing over there?
--Well, if you ____ know, her name is Mabel.
A. may B. can C. must D. shall
The world's economic development is not a win-lose game but one in which all ________ be winners.
A. can B. shall C. must D. would
I really ________ thank you enough. It’s been an wonderful day.
A. needn’t B. should C. must D. cannot
