Can we use will with when?
Also to know is, will used or will use?
Most of the times, the source of the confusion is the perception that “would” is always used as the past form of the auxiliary verb “will”. Yes, “would” is the past form of “will”, but it has various other uses too, which have nothing to do with the fact that would is the past form of “will”.
Regarding this, what tense should I use after when?
In time clauses with words like when, after and until, we often use present tense forms to talk about the future: I'll come home when I finish work. You must wait here until your father comes. They are coming after they have had dinner.
"Could" is a modal verb used to express possibility or past ability as well as to make suggestions and requests. "Could" is also commonly used in conditional sentences as the conditional form of "can." Examples: Extreme rain could cause the river to flood the city.