最近带一位外国友人去游山玩水，在我们交谈的过程中，我经常发现他会用”be supposed to”，当时我就纳闷到底这与”should”有什么区别呢，该怎么去用呢？
1、Should
a common way to give advice
是一种常见的给建议的词
E.g. For your good health, you should start to work out and go to bed before 11:30 at night.
为了你身体健康，你应该开始运动，并且每天晚上11点半前睡觉。
但是要注意措辞和语调，不然很容易说出offensive的话
E.g. You should be more organized with this task.
这个任务你要规划得好些。
I am concerned about that we are getting behind on this task.
我觉得在这项任务上我们有些落后了。
还要注意谈话双方的身份（同级同事，老板对下属等），
2、be supposed to
usually this is more about an outside rule that was established by someone else
在公共场所，公民遵守的一般规则或者是合约规定该遵守的条例。
E.g. You are not supposed to spit on the ground.
你不应该随地吐痰。
As tenants we are supposed to pay the rents on the 10thof every month.
作为租客，我们要每月的10号交付房租。
3、be ought to
This isn’t used much anymore. It may be a bit old fashioned.
这用的不是很多，有一些过时了。
E.g. “You oughta know”is sung by Allanis Morisette.
“你应该知晓”由艾拉妮丝·莫莉塞特演唱。
4、You(‘d) better
This is strong. It’s used to give strong advice or a warning unless you are saying it jokingly.
这个语气会很强硬，一般用于警告类，像妈妈管教孩子一样，除非你是开玩笑。
E.g.You better finish your homework soon if you want to play outside.
如果你想出去玩，你最好快点完成作业。
Your finals are on tomorrow morning? Oh gosh you better get started!
你期末考在明天？天哪，赶紧复习吧！
