The book Practical English Usage by Michael Swan says: The tense in the subordinate clause tends to be simplified.
He gives some examples:
(a) If I (would have) had lots of money, I would give some to anybody who (would ask) asked for it.
(b) In a perfect world, you would be able to say exactly what you (would think) thought.
(c) I would always try to help anybody who was in trouble, whether I knew them or not.
And since Would has the meaning of will just with a softer tone, it got me thinking: What tense should I use when I use would to talk about the present and future, but with doubt, uncertainty, or possibility?
Examples I came up with:
(1) I would go to the park with her if she invites/invited me. =>I want to use "would" to express uncertainty in my willingness to go to the park.
(2) This thing is weird. I would think Tom is/was able to explain. =>I want to use "would" to express uncertainty in my thinking.
(3) I have this extra money on me. I would give it to friends who ask/asked for it. =>I want to use "would" to express uncertainty or possibility of giving money.
Do they have anything to do with tense simplification? If not, does it mean that I can use tenses depending on what I try to say?
By depending on what I try to say, I mean like:
I can use invites in (1) because it happens in the future.
I can use "Tom is able to explain" in (2) because it happens in the future.
And I can use either one of the phrases down below:
(4)use friends who asked for it to mean in the past, there were friends of mine that asked for money from me
(5)use friends who ask for it to mean the friends that might or will ask me for money in the future
Finally, how about could, might, should; I remember they can also be used to express uncertainty, doubt, etc. Do they follow the same rules?