前
[名] ago; front; first; top;
[动] former; （向前进） go forward [ahead];
[例句]比赛将决出前八名。
The matches would decide the top eight.
后
[名] after; back; behind; afterwards; offspring;
[例句]大约3个月后，我就不再对尼古丁上瘾了。
After about three months, I was no longer addicted to nicotine.
