before到底是之前，还是之后？
1. It won't be long before he returns to his native land.
他不久后就会回到祖国。
2.If you miss this chance it will be years before you get another one.
如果失去了这次机会，要许多年以后你才能有这样的机会。
3. A whole month had passes before he fully recovered.
他一个月之后才完全康复的。
