I learned that 'modal'verbs can be contained in one sentence only once. But when I should express two auxiliary verbs in one sentence like 'You can may get this money.', How can we express the same meaning with one modal verb?
3Do you mean something like "You may be able to get this money"? "Be able to" means the same thing as "can" in many contexts, but is not a modal verb.– MorganFRDec 13, 2016 at 14:12
What @MorganFR said. You could also combine the two concepts of ability and possibility with something like You can perhaps get it (or more colloquially, You can/could maybe get it).– FumbleFingersDec 13, 2016 at 14:29
You could also separate one into a subordinate clause: "If he can find his wallet, he may pay the bill" or "He may pay the bill if he can find his wallet"– KysDec 13, 2016 at 18:00
you can do something = you have the ability to do it
you may do something = you have license, permission, or freedom to do it
This would not make good sense:
You have the ability to have the freedom to do something.
Having no restrictions imposed on you is not an ability of yours. It is a condition external to you.
When the traffic light turns green, you may cross the street.
If you are able to walk, you can walk across the street.
If you are crippled, you may be able to cross the street before the red light. May can convey "possibility", not just permission.– MorganFRDec 13, 2016 at 14:46
@MorganFR you added 'be able to', i think this adds the 'possibility'. Consider: May I swim across the lake? Yes, you may - I allow you too. Yes, you may be able too - sounds odd. Dec 13, 2016 at 16:01
Yes of course @SovereignSun, but that was the whole point of the OP's question as far as I know.– MorganFRDec 13, 2016 at 16:22
@MorganFR: True, maybe you can cross the street safely if there's a gap in the traffic, even if you don't have a green light. You may|might be able to do it.– TᴚoɯɐuoDec 13, 2016 at 18:34
You can may get this money.
The sentence is ungrammatical; you don't use two modal auxiliaries together in front of a verb. You should use either can or may.
You can get this money = You are able to get this money. It may mean "You are allowed to get this money".
You may get this money = It is possible for you to get this money. It may mean "You are allowed to get this money".
However, "can" is more commonly used than "may" for giving permission.