should, ought and had better

Advisability (可勸性):

must (必須) > have to (需要) > ought to / should (應該) > had better (最好...)

Explanation (解釋):

1. MUST: It is absolutely necessary to do something.
2. HAVE TO: It is necessary to do something.
3. OUGHT TO / SHOULD: It is good to do something.
4. HAD BETTER: It is better to do something.

Example (例子):

1. You must finish your homework before sleep.
你必須在睡覺前完成你的家課。

2. You have to finish your homework before ten.
你需要在十時前完成你的家課。

3. You ought to / should finish your homework before playing computer games.
你應該要在玩電腦遊戲之前完成你的家課。

4. You had better finish your homework after school immediately.
你最好於放學回家之後立刻完成你的家課。

Remarks (備註):
For native English speakers, they often use the word "should" to express something is good to do in oral English. In fact, the phrase "ought to" has the same meaning as the word should , however, it is not commonly used in oral English. The phrase "ought to" is mainly used in formal written English.

must > had to > ought to = should