If Clause With Modals?

AnonymousIf I can touch you, I will be happy.
If I might speak, you will understand.

Sometimes I hear the expression 'if i may add', is this not correct?

These are common.

"If I may/might add," is usually casual - conversational - especially when used in the middle of a sentence ("sentence interrupter"?).

I think it would be safe to say that your examples all refer to future time.

AnonymousI was wondering if we could use other modals like 'could', 'can', 'may', might, should. Do you think so?

Yes. Under the right conditions you can use any of the modals in an if clause; however, some of them give the impression an old-fashioned style.

can and could are probably the most common.

You'll feel right at home in Mexico if you can speak Spanish.
If I could help you, I would.

CJ

Thank you, Avangi and CJ. Your explanations were really helpful.

AvangiI think it would be safe to say that your examples all refer to future time.

Could you please explain further? Isn't 'might' referring to past time, though 'will' refers to future time in my example sentence "If I might speak, you will understand"?

Is it possible and correct to mixed modals (past and future) like in the following?

You'll feel right at home in Mexico if you could speak Spanish.
You would feel right at home in Mexico if you can speak Spanish.

AnonymousYou'll feel right at home in Mexico if you could speak Spanish.
You would feel right at home in Mexico if you can speak Spanish.

No, no, no!

can goes with will; could goes with would.

Any exceptions you see to this pattern are either wrong or exceptions! Don't invent your own exceptions!

CJ

AnonymousYou'll feel right at home in Mexico if you could speak Spanish.
You would feel right at home in Mexico if you can speak Spanish.

The first one surely doesn't work, but the second one sounds perfectly natural to my ear.
Perhaps "exception" is in the ear of the "hearer."

To me, in this context, "if you can" does not assume that you can't.
I think it functions grammatically in the same way as "since you can speak Spanish."

I hear two separate propositions here:

(1) It's not a certainty at this point that you're going to Mexico.
(2) One argument in favor of your going is that you can speak Spanish.

If this is an exception, then Viva la exception!"

AnonymousCould you please explain further? Isn't 'might' referring to past time, though 'will' refers to future time in my example sentence "If I might speak, you will understand"?

The danged modals have various meanings.
In this usage, you're asking permission to speak in the future.
"If I might have a word with you, Miss Jones." To tell the truth, I don't even know if it's a sentence.

I suppose it's a bit old fashioned, but so am I. I think these things are still said by some of us, and we expect the rest (of us) to understand.

AvangiPerhaps "exception" is in the ear of the "hearer."

There's always one in every crowd! Well, go ahead and encourage the complete collapse of the English language into utter chaos, if you must!

CJ

CalifJimutter chaos

I feel your pain, but mine comes from knowing that when accompanied by context, these things wouldn't raise an eyebrow.
Life is contextual, isn't it?

Best regards, - A.