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第49页

信息发布者：

ake

ust

tudents

ustn't

mustn't/can't/

shouldn't

作业精灵老师示例

S1：To cross the road safely, what must you do?

S2：I must look for a zebra crossing and look at the traffic lights.

S1：To cross the road safely, what mustn't you do?

S2：I mustn't play football on the road or play on the zebra crossing.