Ответ: 1) If it rains, we might stay at home
It might rain.
2) When you arrive at the airport, please call me.
You are expected to arrive.
3) When you see Paul, tell him i say 'hi'.
You will see Paul.
4)They will be back soon if there's no traffic.
There will not be traffic.
5) When the letter arrives, I will call you.
The letter will arrive.
6) Frank will love this film if he sees it.
Frank will see the film.