Intermediate grammar exercise: positive and negative forms of modal verbs

English grammar practice exercise, for intermediate learners.

In this exercise you will practise modal verbs in their positive and negative forms.

Instructions: Complete each sentence using one of the following modal verbs:

can, can’t
must, mustn’t
have to, don’t have to

questions go herescore goes here

Modal verbs: negative forms
positive negative
can (used for possibility)
It can happen; everything's possible.
can't (cannot)
It can't happen; it's impossible.
can (used for permission)
Can I smoke here? ∼ Yes, you can.
can't (cannot), mustn't
You can't smoke here. You mustn't smoke here.
can (used for ability)
I can play the guitar.
can't (cannot)
I can't play the guitar.
must, have to (used for obligation)
You must be there at 8 o'clock.
You have to be there at 8 o'clock.
don't have to, needn't
You don't have to be there at 8 o'clock.
You needn't be there at 8 o'clock.
must (used for personal opinion, certainty)
He must be here somewhere – his car is outside.
can't (cannot)
He can't be here – his car's not outside.
might, may (used for personal opinion, certainty)
He might/may be late today – there's a lot of traffic on the roads.
may not, might not
He might/may not get here on time – there's a lot of traffic on the roads.
should (used for weak obligation / advice)
You should stop smoking because it's unhealthy.
shouldn't (should not)
You shouldn't smoke so much – it's unhealthy.


  1. Anonymous - May 14, 2016, 11:20 am Reply

    Really good website especilly for helping kiddies learn the rules and making a poster as my kid used it for that as homne work for school.

  2. sg - May 31, 2016, 8:39 am Reply

    Great exercise. In sentence 10 I believe the word “yet” needs to be taken out.

    • Anonymous - January 17, 2017, 2:48 pm Reply

      no sentence 10 is ok with yet. But, sentence 11 should probably use into or to instead of in.

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