will和begoingtobedoing的区别（besupposedto用法精讲）

老师应该对所有的学生一视同仁。

【核心词汇】sup‧pose v. / sə'pəʊz /

• be supposed to do / be sth

used to say what someone should or should not do, especially because of rules or what someone in authority has said 应该做某事/是某事物

• We’re supposed to check out of the hotel by 11 o’clock.
• 我们应该在 11 点之前从酒店退房。

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。

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。

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”。

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。

be supposed to后面接“have 过去分词”时，表示“本应该做某事而没做”。

You are supposed to have handed in your homework by now.

现在你应该已经把作业交上来了。

He is supposed to have arrived an hour ago.

他应该一小时前就到了。

He’s watching TV? He’s supposed to be cleaning his room.

他正在看电视? 他应该在收拾自己房间才对啊。

We were supposed to have a chemistry class， but the teacher was out of town for a meeting.

我们本应该上化学课， 但老师出城开会去了。