1
I must to go to London.
I must go to London.
You should going to London.
You should go to London.
I can’t to come with you.
I can’t come with you.
After a modal verb such as can, must, should, may, might or will, use the infinitive without to: ‘must go’, ‘should study’, ‘can come’. Do not use to or the -ing form after a modal verb.
2
Do you can dance?
Can you dance?
You don’t must call me before 9 a.m.
You must not call me before 9 a.m.
Modal verbs are auxiliary verbs, so do not use do/does/did to form questions or negative sentences.
In questions, put the modal verb before the subject: ‘Can you dance?’ ‘Should we leave?’
In negative sentences, put not after the modal verb: ‘You must not call.’ ‘She cannot come.’
Must not means that something is prohibited: ‘You must not call me before 9 a.m.’
Don’t have to has a different meaning. It means that something is not necessary: ‘You don’t have to call me; you can email me.’
Check our grammar lesson on have to, don’t have to, must and mustn’t.
3
When you arrive at the office, you will must put on your tie.
When you arrive at the office, you will have to put on your tie.
When you finish your training, you will can run much faster.
When you finish your training, you will be able to run much faster.
We do not normally put two modal verbs together.
After will or another modal verb, use have to instead of must, and be able to instead of can: ‘She might have to work late.’ ‘He may be able to help.’
Check our grammar lesson on can, could and be able to.