What's the difference between have to, supposed to and ought to?
When you must do something, you have to do it. It is used for a situation that has no choice. Have to is used for obligations.
"Students must wear their uniforms to school or they will be sent home."
"In England, you have to drive on the left."
Supposed to is used when we are talking about our obligations. Use supposed to when saying what is the best thing to do in a situation; the correct way of doing things. For example, use supposed to for cultural rules and expectations.
"You are not supposed to talk loudly in a library."
"I totally forgot I was supposed to call you last night, sorry."
When we should do something, but we do not have to do if, we ought to do it. It is not as strong as must. Ought to is not usually used in questions or negative sentences. Use it to advise or make recommendations.
"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."
Now decide which words are needed to complete these sentences: