H. use for + a period of time to say how long something goes on. (e.g. for two hours)
a. For is a preposition which is used with a period to say how long something goes on. (e.g. Simon has been sleeping for 8 hours.)
H1. use during + noun to say when something happens. It does not tell us how long it happened. (e.g. Nobody spoke during the presentation.) Cannot use during to say how long something goes on. (e.g. It rained for three days without stopping. (not during three days)
H2. While (+ subject + verb) is used to talk about two things that are happening at the same time. The length of time is not important. (e.g. The phone rang while I was watching TV.)
a. When you are talking about the future, use the present (not will) after while. (e.g. What are you going to do while you are waiting? (not while you will be waiting))