1.
Three days ago.
三天以前，大前天。
2.
an age ago
一代人以前, 多年以前
3.
pickpockets, formerly known by the denomination cutpurse.
扒手，以前称作cutpurse。
4.
-Two, three months ago.
- 两三个月以前.
5.
(combining form) former.
（构词成分）以前的。
6.
coming next after the eighth and just before the tenth in position.
位于第八以后第十以前。
7.
coming next after the seventh and just before the ninth in position.
位于第七以后第九以前。
8.
B: Was. Past tense. Former life.
以前是。过去式了。以前的生活是这样。
9.
He used to keep his diary in the evening.
他以前习惯晚上写日记。
10.
He used to go out at night.
他以前常在晚上出去。
11.
It(The sun) will burn off before noon.
中午以前天会放晴。
12.
propel oneself through the water in a finning motion.
在水中挥动鳍以前进。
13.
It costs double what it did.
这东西比以前贵两倍。
14.
I've heard the story before.
以前,我听说过这个故事。
15.
I have never heard of the man before.
我以前从未听说过此人.
16.
I won't be back till 11:00.
11 点以前我回不来。
17.
I have to be in by ten.
我必须在10 点以前离开。
18.
The advance guard was pressing forward with all speed.
前卫正以全速向前挺进。