九年级全册英语 Unit10 supposed to

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　　为了方便大家学习英语知识，小编特意为大家准备了九年级全册英语 Unit10 supposed to知识点，供大家参考学习。

九年级全册英语 Unit10 supposed to

　　用法一：be supposed to... 其中to是动词不定式符号，不是介词，其后要跟动词原形。 当be supposed to... 的主语是“人” 时，意为“应该......;“被期望......，它可以用来表示劝告、建议、义务、责任等，相当于情态动词should。

　　如：

　　Everyone is supposed to wear a seat-belt in the car. 每个人在汽车里都应该系安全带。

　　Teachers are supposed to treat all the students alike. 老师应该对所有的孩子一视同仁。

　　用法二：当be supposed to... 的主语是“物”时，它表示“本应;本该”，用于表示“某事本应该发生而没有发生”。

　　如：The new laws are supposed to prevent crime. 这些新法令本应该起到防止犯罪的作用。

　　The train was supposed to arrive half an hour ago. 火车本应在半小时之前到达。

　　用法三： be supposed to后面接“have + 过去分词”时，表示“本应该做某事而没做”。如：You are supposed to have handed in your homework by now. 现在你应该已经把功课交上来了。

　　He is supposed to have arrived an hour ago. 他应该一小时前就到了。

　　用法四： be supposed to... 的否定结构为be not supposed to...,它常用于口语中，意为“不被许可;不应当”。

　　如：

　　She was not supposed to be angry about that. 她本不该为那件事而生气的。

　　You are not supposed to smoke on the bus. 你不应该在公共汽车上吸烟