Talking about complete possibility

The auxiliary verbs that can be used to express complete certainty are shall, will, can, could and must.

  • There is the phone. That will be Ram.
  • I shall come tomorrow. OR I will come tomorrow. (Both shall and will can be used with I and we. There is no difference in meaning.)
  • He will come.
  • It will rain this evening.
  • It won’t rain this evening.
  • There is the doorbell. Who can it be? Well it can’t be James – He is in Delhi.
  • You must be tired. I will get you something to drink.
  • I will buy a car if I get my rise.
  • She will come if you invite her.

Expressing probability and possibility

We can use the auxiliary verbs should, ought, may and might to talk about possibility and probability.

  • She should be here soon.
  • She may come.
  • It may rain this evening.
  • We may go camping next week.
  • She ought to know better.
  • I may buy a car.
  • You should be able to solve the problem.
  • She may buy that house.
  • I should be able to finish this job by Monday.


Might shows less possibility than may.

  • She might come. (Perhaps a 20% chance)
  • She may come. (Perhaps a 50% chance)