Thank you, all my teachers here. One more question:If I say 'if I ever have enough time, I write to my parents every week', will there be any diference in meaning?
The writer is suggesting that it is unusual for him/her to have enough time.
If I say 'if you're ever in Seattle, come and see me', does it implies that I don't think you will be in Seattle someday? (but I think it's a little strange, why bother asking?)
If I say 'if you ever do that again...', implying that I don't think you dare do that again?