Modal Verbs

There are ten modal verbs in English:

  • can
  • could
  • may
  • might
  • shall
  • should
  • will
  • would
  • must
  • ought to

To use Modal Verbs correctly, follow these rules:

  • They do not change forms like other verbs: go, goes, went, gone / look, looks, looked, looked.
  • There is no do / does in the question forms. Can you give me a hand?
  • There is no don't / doesn't in the negative forms. He shouldn't do that.
  • They are always followed by a base form verb. "Ought to" is the only exception as it takes "to" or "not to" before the verb. We would help if we had time. She mustn't do that! We ought to get going.
  • They do not usually have past or gerund forms. Other verbs are used instead. I hate having to get up early. (must) I was able to play piano better when I was a child. (can)
  • Some modals are used with the Perfect Infinitive to make past forms. This is more explained in Unit 10. You shouldn't have done that. She must have stayed home.

Modal Verbs of Probability: Present and Future

To express probability or certainty about the present or future, we use the following modal verbs. They are listed in order of certainty.

Must

Must is what we use when we want to say when we are certain about something, but we do not have all the facts.

  • You must be joking if you think I can do that!
  • The meat must be ready by now. Let's check!
  • You must be cold if you're wearing a coat in this weather.

Can't

The negative of this use is can't, not mustn't.

  • You can't be cold! It's almost thirty degrees outside!
  • He can't be here already. He left only twenty minutes ago.
  • That can't be true!

Should

Should expresses the speaker's expectation. The expectation is always wanted.

  • The weather should be pretty nice tomorrow.
  • My team should win the game tonight.
  • It shouldn't snow too much in the winter.
  • She should be coming soon.

Should in this use expresses what we want to happen. It is not common to use should to talk about unpleasant or unwanted events.

  • You should get hurt if you continue doing that. NO
  • I think you'll get hurt if you continue doing that. YES
  • The people should die if they don't get help soon. NO
  • The people will die if they don't get help soon. YES

May

May expresses that the present or future is possible.

  • She may be sick if she needs to talk to a doctor.
  • We may come tonight if we have time.

Might

Might is a little less certain or unsure than may.

  • I guess they might come. I doubt it though.
  • She might be upstairs. I'll check.

Perhaps or maybe...(will) is also used with the meaning of may or might.

  • Maybe I'll come if I have time.
  • Perhaps she is sick if she needs to talk to a doctor.
  • Perhaps they'll come. I doubt it though.

Could

Could has a similar meaning to may or might.

  • She could be here. I haven't seen her though.
  • The store could be really expensive. I'm really not sure.

Couldn't is used to express present probabilities. It is slightly weaker than can't.

  • He couldn't be in this class already. His level was so low two months ago.
  • It couldn't be raining right now. It was beautiful and sunny this morning!

Couldn't is not used to talk about the future. Instead, we use might not.

  • She might not come to the party tomorrow night if she's still sick.
  • John might not be going on his trip. He broke his leg recently.
  • That film might not be very good. I have heard some bad things.

Exercise

Please click the Exercise link to continue.

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