You needn't come with me if you don't want to. You...
You don't have to/don't need to come with me if you don't want to.
It isn't necessary to go to the immigration office. I....
I needn't /don't have to/don't need to go to the immigration office.
Perhaps they come up with a better solution next week. They...
They may/might/could come up with a better solution next week.
It looks like he is looking for something. He...
He may/might/can/could be looking for something.
I'm sure that David is sick. David ....
David must be sick.
Maybe Tom is looking for a new place to live. Tom...
Tom could/may/might be looking for a new place to live.
It would be a great idea if Harry took a holiday. Harry...
Harry should /ought to take a holiday.
Students are not allowed to leave the classroom. Students...
Students mustn't/can't leave the classroom.
I'm sure that Brenda isn't over thirty. Brenda...
Brenda can't be over thirty.
Why aren't you at home revising for your exam? You...
You should/ought to be revising for your exam at home now.
You're not allowed to park here. You...
You can't/mustn't park here.
It is a bad idea to go into that abandoned castle at night. We...
We shouldn't go into that abandoned castle at night.
I'm sure Stella is at the lecture right now Stella...
Stella must be at the lecture right now.
I'm sure that Helen feels really lonely. Helen...
Helen must feel really lonely.
Maybe Paul is arranging the ceremony for Friday. Paul...
Paul might/could/may be arranging the ceremony for Friday.
I would like to have the ability to speak many foreign languages. I...
I would like to be able to speak many foreign languages.
Do I need a different driving license for a motorbike? Do I...
Do I have to have a different driving license for a motorbike?
Perhaps Pam and Tim decide not to come to the party. Pam and Tim ....
Pam and Tim might/may not come to the party.
Did you manage to stop him? Were...
Were you able to stop him?/Were you able to stop him?
The minister .............fight for the rights of people. (ability in the past)
The minister could/was able to fight for the rights of people.