Hello Happy,
I am not a teacher. However, I would like to address your problem:
You will have to keep certain points in mind regarding BE.
1) BE has several meanings like any other verb. see its meaning in
Dictionary.com | Find the Meanings and Definitions of Words at Dictionary.com
2) BE represent a state. He is happy, he is better now, he is not feeling well.
2) BE comes before adjectives, adverb and a noun also.
He is happy (Adjectives), He is there (Adverb). He is a doctor. (Noun)
3) BE equate the situation.
eg. He is like a Monkey. He = Monkey
4) BE basically a connector. It connects subject with the adjective, adverb and a noun.
5) BE is the base form verb. when any tense comes, BE becomes is, am are, was, were, been according to the situation.
6) In a sentence or a phrase only only finite verb comes, other becomes nonfinite.
7) whenever model comes, base form of
BE / any other verb will be used before adjective, adverb and before a noun
Now in your examples,
1) You may come as you wish.
we did not use BE because like any other verb, BE is also a verb. Now here come is a verb, so there is no use of BE here.
See point 7
2) This coat may be David's
In this sentence meainging of be is belongs to
This coat may belong to David.
We have used base form. After model base form comes.
3) How old may she be.
in this example, we are asking about age. Suppose she is 60 years. We are equating her age. Her age = 60 years. now model came in ur sentence, base form of be is used.
I hope this help you to some extent.
First if all I'm very thankful to you Sir after giving answer to me after many days.
OK Sir, I've understand that "might" uses for past and "may" uses for present. But I'm still unclear that why we use "be" with both may and might? What's "BE"? Why we use it? Where it has come from?
Here are some examples:
Talk about May first:
You may come if you wish? Why we didn't use be with may here?
This coat may be David's? Why we used be with may here?
How old may she be? Why we used be with may here?
May you both be very happy. Why we used be here again?
Now talk about Might:
Might I suggest another time. Here are we talking about past? Why might came here and why be didn't come here?
That might be our taxi. So is this sentence using past? and why it's not using be with it?
He might just possible have lost his keys. So is this MIGHT talking about past here? and why it's not using be here?
Please explain me all this. I'll be grateful to you.
Regards,