may/might For present or future possibility, normally either can be used. might slightly increases the doubt (see Thomson and Martinet, ďA Practical English Grammar.Ē
When asking permission, either can be used (also can / could) but there is a distinct difference:
May I open the window? for example, implies that you have reason to believe that the person youíre speaking to will probably agree to your opening the window.
Might I open the window? implies that you think the other person could object to your opening the window. For this reason, might I can sometimes sound obsequious or sarcastic in a situation where the other person is sure to agree.
The oral contraction mustnítíve (where have is an auxiliary)
In spoken English the contraction would be made but not in written English, where you would normally have mustnít have. However you have to be careful about the use of this structure for speculation about past events:
If you think that something was very possibly true you use must have + past participle:
Heís late. He must have missed the train.
If you think that something was impossible, you use canít have:
He canít have missed the train. He phoned me from the station well before the train was due to arrive.
However, I have heard mustnít have being used by native speakers instead of canít have. It must be entering the language.
Respond to the following with a formula denoting doubt or confession of ignorance. Make up a sentence using may (might) followed by an infinitive to express a supposition implying uncertainty. Use the Perfect Infinitive after may to express an action referring to the past.
0. He might have already made an appointment with Mr. Smith. (He said he would.)
1. Lucy was eager to go home for the holidays. And I’ve just seen her at the demonstration. What’s happened?
I don’t quite know. She may’ve changed her mind. Sofia is too far off to go there for three days only.
2. The wedding day is drawing near. Where will John get white roses for his bride in winter?
I haven’t the least idea! His friends might (may) bring them from the Caucasus. I hear they are coming.
3. The bell has gone and Betty is not here! What’s the matter?
How do I know? She may (might) be still sleeping. There is something wrong with her alarm clock.
Might denoting uncertainty has no temporal meaning. The time of the action is indicated by the form of the infinitive.
In spoken English might often stands for may in reference to present of future time to express greater uncertainty on the part of the speaker.
Might with the Perfect Infinitive is often used to express a reproach, or a possibility in the past which exists no longer.
4. He may have been hurt. (We do not know yet whether he was , or was not.)
5. He might have been hurt. (But luckily he was not.)
May expressing possibility due to circumstances.
6. In this museum you may see very interesting things.
7. You may see him every morning walking with his child.
Might expressing reproach. Only might is used in this meaning but not may.
8. It’s you, Mother! I’ve fallen a sleep waiting for you.
I see. You might, at least, have put the kettle on to boil. You know how tired I am after a long day’s work.
9. Sorry I’ve broken my promise, dear, but I couldn’t possibly come last night.
Anyway, you might’ve warned me you were not coming. You know my telephone number, don’t you!
10 . You might lend me a razor. I was shaved this morning with a sort of bill-hook.
bill-hook = an implement with a curved blade attached to a handle, used especially for clearing brush and for rough pruning.
When might is used with the Indefinite Infinitive it is rather a request made in the tone of a reproach, as the above example shows. Ehen it is used with the Perfect Infinitive, it expresses reproach.
11. I realize now how you spent your days and why you were do forgetful. Tennis lesson, my eye. You might have told me, you know.
The form might besides being the Past Indefinite Indicative of the modal verb may is often the Past Subjunctive retaining its modal meaning. As the Past Subjunctive it is used with the Indefinite and the Perfect Infinitive.
12. If you were engaged and you found you loved somebody better, I might go cracked but I shouldn’t grudge it you.
13. Why did I let my brother go alone? Should I ever see him alive? I might have known from the dog’s actions that something dreadful was about to happen.