Instead of would here it is possible to use could (ability or possibility), should (obligation) or might (possibility).

George could have won the race if his shoelace hadn’t come undone.

Instead of would here we can use could (permission or ability), might (certainty/uncertainty) or should (obligation).

If you were taller, you could play for the Lakers.
If you weren’t under 18, I should punish you.

Instead of will here we can use may/might (certainty/uncertainty), may (permission), can (permission or ability) or must/should (obligation).

The auxiliaryA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") may is used to express contrast.

You may be right, but that is no excuse for shouting like this. (Although you are right, that is...)

Try as somebody may (present reference) and try as somebody might (past reference) mean however hard I try/tried...

Compare these two sentences:

To express past criticism the same auxiliariesA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") are used as in the case of present criticism. However, the infinitives that follow are perfectThe aspect expressing completion. E.g.: He’s finished university. infinitives.

To show disapproval, the auxiliariesA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") can, could, might and should/shouldn't are used.

You can be really annoying, you know! 
You shouldn't be sitting here just doing nothing!
You might be more polite!
George could really help you!

To express past certainty, the same auxiliariesA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") are used as in the case of present and future certainty. However, the infinitives that follow are perfectThe aspect expressing completion. E.g.: He’s finished university. infinitives.

Here we discuss structureThe way in which the parts of a sentence, clause or expression are arranged. E.g.: make somebody + infinitive in "The teacher made me rewrite the composition."s that show how certain the speaker is whether something happens or will happen. Between the two extremes (the first and the last sentence below) the order of the structures (might, may, could etc.) expresses a growing amount of certainty.

Normally, the auxiliariesA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") of permission, possibility and willingness are used to express requests.