Modal verbs

Is used to express strong obligation

You must wear a mask in public places.

Students must attend their classes.

The teacher must check the homework.

Have to is also used to express obligation.

We have to wear a mask in public places.

Students have to do their homework.

The teacher has to check the homework

Students mustn't cheat in the exam.

You mustn't go into supermarkets without a mask.

Couples must not cheat on each other.

DON'T HAVE TO

You don't have to use a mask in your car.

You don't have to go to the doctor every day.

Laura doesn't have to do the exam.

DON'T NEED TO / NEEDN'T

You don't need to use a mask in your car.

You needn't use a mask in your car.

Must we use a mask in public places?

Do we have to use a mask in public places?

Does the president have to quit?

Must the president quit?

Mild obligation, advice.

You should pay attention to the teacher.

The teacher should give an extra point to good students.

Students should not skip classes.

Jose shouldn't turn off his camera.

Should the teacher finish the class early?

should = ought to | shouldn't = ought not to

You ought to pay attention to the teacher.

The teacher ought to give an extra point to good students.

Students ought not to skip classes.

Jose ought not to turn off his camera.

Ought the teacher to finish the class early?

Strong advice

You had better pay attention to the teacher.

The teacher had better give an extra point to good students.

Students had better not skip classes.

Jose had better not turn off his camera.

I'd better finish the class early.

She'd better do her homework.

Strong advice

You are supposed to pay attention to the teacher.

The teacher is supposed to give an extra point to good students.

Students aren't supposed to skip classes.

Jose isn't supposed turn off his camera.

I'm supposed to finish the class early.

She's supposed to do her homework.