All good actors are very bright. You can't be stupid and a good actor. You may be inarticulate, you may not be highly educated, but all good actors are quick-witted, some of them dazzlingly so. All you do is guide them.
I mean, the first 'Back to the Future' is kind of a perfect script, I think, in terms of handling time travel the best. It depends on your definition. To me, that means it effectively uses it in the story.
A stricken tree, a living thing, so beautiful, so dignified, so admirable in its potential longevity, is, next to man, perhaps the most touching of wounded objects.