—To make our city more beautiful rubbish into the river. —I agree.A. needn’t be thrownB.

问题补充：

—To make our city more beautiful, rubbish into the river.

—I agree.

A. needn’t be thrown

B. mustn’t be thrown

C. can’t throw

D. may not throw

答案：

A. needn’t be thrown

(答案→)B. mustn’t be thrown

C. can’t throw

D. may not throw

解析：考查情景交际和情态动词。“为了让城市变得更美好，垃圾禁止被扔进河里。”“同意。” needn’t“不必”；mustn’t“禁止”；can’t“不能”；may not“可能不”。rubbish和throw之间是动宾关系，故用被动语态，先排除C、D；A项语气不强。故选B。