HAVE TO/MUST - BE SUPPOSED TO - OUGHT TO
I. HAVE TO/MUST implies that you don't have a choice.
"HAVE TO/MUST" ngụ ý rằng bạn không có sự lựa chọn.
John has to go to work everyday.
The students have to study tonight.
Students must wear their uniforms to school or they will be home.
In England, you have to drive on the left.
Willy needs money to pay for his food and house. If he doesn't go to work, he won't have money. He must work. => Willy has to go to work.
Joan want to be a nurse. To become a nurse it is necessary to go to nursing school.
=> Joan has to go to nursing school if she wants to be a nurse.
II. BE SUPPOSED TO means an obligation. It is something that you should do, or something that another person expects you to do. Because it is the best thing to do or the correct way of doing things in that situation.
"BE SUPPOSED TO" có nghĩa là một nghĩa vụ/bổn phận. Đó là việc mà bạn nên làm, hoặc một việc mà người khác mong đợi bạn sẽ làm. Vì đó là việc tốt nhất, là cách đúng nhất/tốt nhất để làm trong hoàn cảnh đó.
Sally is supposed to meet her friend tonight.
All of the employees are supposed to attend today's meeting.
You are not supposed to talk loudly in a library.
I totally forgot I was supposed to call you last night, sorry.
You see, Nick, babies are supposed to be born head first, but sometimes they're not.
=> It's a law of nature.
Tom's friend is waiting for him at the gym. They made plans to meet at 6:00. His friend will be upset if Tom doesn't go. => Tom is supposed to meet his friend.
III. OUGHT TO means a suggestion or a piece of advice. You should do something, but you don't have to do it if you don't want. It is not usually used in questions or negative sentences.
"OUGHT TO" có nghĩa là một lời đề nghị hay một lời khuyên. Bạn nên làm một việc gì đó, nhưng bạn không phải làm việc đó nếu bạn không muốn. Không được dùng thường xuyên trong câu hỏi và câu nghi vấn.
We ought to clean the house tonight.
Phillip ought to help you with your homework.
You ought to email Mike and say thanks for the nice present he bought you.
We ought to wear sunglasses, I think it's going to be a very sunny day.
Johnny should help his mother with the housework. His mother would be happy if he did. But if he didn't help her, his mother wouldn't feel bad. => Johnny ought to help his mother.
Lisa tells Nathan that he would be a good manager. She suggests that he apply for a job as a manager. Nathan is going to think about that. => Lisa thinks Nathan ought to be a manager.
Tóm lại:
I have to do my homework.
-> If I don't, will be in trouble.
I am supposed to do my homework.
-> If I don't, my teacher will notice that I didn't do it.
I ought to do my homework.
-> I don't have to if I don't want to, but I feel I should do it because I want to do well in the class.
Tương tự:
- Everyone in our country has to/must carry an identity card on them.
-> This implies that people usually obey the rule, and you have to/must do.
- Everyone in our country is supposed to carry an identity card on them.
-> This implies the law is not rigidly observed, but you should do.
- Everyone in our country ought to carry an identity card on them.
-> This implies the law is not obligatory, and you don't have to carry the identity card on you if you don't want.