1.Ought to 後接動詞原形，表義務，但不及must 那樣具有信心，如：
You don’t look well. You ought to go to see the doctor.
你氣色不好，應該去看病。
2.Ought to 用於否定句，其否定形式可縮略為oughtn’t ，如：
You oughtn’t to smoke so much. 你不應該抽這麼多煙。
3.也可以用於疑問句，如：
Ought you to smoke so much?你應該抽這樣多煙嗎？
4.Ought to 在間接引語中表過去時形式不變，如：
He said you ought to tell the police.
他說你應該去報告警察。
5. ought to表示責任和義務，意為“應該”，語氣比 should強；還可表推測。
You ought to finish your work before you go home.
You ought to obey your parents when they are right.
You have practiced for a long time. There ought to be no difficulty for you.
6.ought to have done sth, should have done sth
本應該做某事，而事實上並沒有做。否定句表示"不該做某事而做了"。
You ought to (should) have been more careful in this experiment.
He ought not to have thrown the old clothes away.（事實上已扔了。）
ought to 在語氣上比should 要強。
1.Ought to 後接動詞原形，表義務，但不及must 那樣具有信心，如：
You don’t look well. You ought to go to see the doctor.
你氣色不好，應該去看病。
2.Ought to 用於否定句，其否定形式可縮略為oughtn’t ，如：
You oughtn’t to smoke so much. 你不應該抽這麼多煙。
3.也可以用於疑問句，如：
Ought you to smoke so much?你應該抽這樣多煙嗎？
4.Ought to 在間接引語中表過去時形式不變，如：
He said you ought to tell the police.
他說你應該去報告警察。
5. ought to表示責任和義務，意為“應該”，語氣比 should強；還可表推測。
You ought to finish your work before you go home.
You ought to obey your parents when they are right.
You have practiced for a long time. There ought to be no difficulty for you.
6.ought to have done sth, should have done sth
本應該做某事，而事實上並沒有做。否定句表示"不該做某事而做了"。
You ought to (should) have been more careful in this experiment.
He ought not to have thrown the old clothes away.（事實上已扔了。）
ought to 在語氣上比should 要強。