I'd like to know if I am right, please: the verb CAN can be used in the Past (COULD), in the Present (CAN) and in the Conditional (Could). Since the verb CAN can't be used in the Future, we substitute it by WILL BE ABLE TO or MAY, being careful not to change the meaning. MUST can be used in the Present. In the past we use HAD TO, in the Future we use WILL HAVE TO and in the Conditional, we use WOULD HAVE TO. We use SHOULD in the Past, SHALL in the Present, SHOULD in the Conditional, but what do we use in the Future? And what about MAY and Might? And OUGHT TO? Is there a chart showing the anomalous verbs, the tenses they can be used and the substitutions we can make in the tenses they can't be used? Thank you very much! Hugs!

3 Answers


SSimmons 480

In your example, you are using words that are more commonly called modal verbs or modal auxiliaries. As most English students do, you are trying to narrow these words to a single meaning or function. Most of these words have several functions: ability, obligation, need, possibility, probability, request, condition, offer, advice, opinion, and permission. Depending on their function, they can all be substituted for other words or phrases. I'm assuming certain fuctions, based on how you've grouped the words.

  • Your first sentence seems to be referring specifically to ability and makes correct assumptions of the modals in that context.
  • Your second sentence seems to be referring to obligation and need. The different forms of HAVE TO that you are using only work in the affirmative and interrogative. To talk about obligation in the negative, except in the present, you would use MAKE, LET, ALLOW or COULDN'T.
  • Your third sentense seems to be referring to advice and offers. We use SHOULD HAVE in the past, SHOULD (advice) or SHALL (offer, but only used with I and WE in all cases) in the present and future. OUGHT TO is usually included here to refer to advice and can substitute SHOULD.
  • MAY and MIGHT usually refer to probability and (un)certainty. They can be used alone for the Present and Future, and with HAVE in the past.

Although I don't know of a chart, the book "First Certificate Language Practice" Does an excellent job of explaining these difference and giving exercises to practice them. I hope this helps you.


Thank you, SSimmons!


ahenus 11540

modal verbs in present tenses: - can / be able to - may - must - have to / has to may refers to present/close future and bears less possibility than can.

modal verbs in past tenses: - could - had to

modal verbs in future: - will be able to - will have to - might difference between might and will is that might is less likely to happen.

modal verbs in (second) conditionals: - should - would - could (i regard it as a combination of can+would since the meaning is also the combination of these two) - would have to - might

all of these are learned/picked up/figured out, i'm not a native speaker.


Thank you, ahenus!


you're certainly welcome :)


As far as I recall from my use of English classes, the "May" and "Might" were a 75%/25% chance of something happening... "Today I may go to the zoo" -> It's likely I'll go "Today it might rain" -> There's a slim chance that it will rain


Thank you, Curdo!

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