二. 单项选择(每小题1分，共20分)
( ) 21. To make our city more beautiful, rubbish ______ into the river.
A. needn’t be thrown B. mustn’t be thrown
C. can’t throw D. may not throw
( ) 22. —I won’t come to the party unless Tom __, too.
—You mean if Tom comes, you’ll come.
A. will invite B. invites C. invited D. is invited
