before的用法

Question

three thousand years before that这个before是介词还是副词？
before有这个用法么？我找了3本语法书都没找到

Answer 1

prep.
1. 在...以前
Only two days remained before the examination.
考前只剩下两天了。
2. (指顺序、重要性等)在...之前,先于
Your name comes before mine.
你的名字在我之前。
Pride comes before a fall.
骄必败。
3. 由...考虑中
We will put the matter before the committee.
我将把此事提交委员会考虑。
4. 在...前面;在...面前
She said she had never spoken before an audience.
她说她从未在大庭广众讲演过。
ad.
1. 较早
Come at two o'clock, not before.
两点钟来,不必再早了。
2. 以前;曾经
He was never late before.
过去他从不迟到。
Have you two met before?
你们两人以前见过面吗?
3. 在前;向前
Several soldiers went before to scout.
数名士兵在前面探路。
conj.
1. 在...以前
Check it carefully before you hand it in.
交来之前仔细核对一下。
2. 与其...宁可
I'd die before I'd tell.
我宁死也决不会说出来。
3. 否则,要不然
Get out before I call the police.
滚开,否则我叫警察。

Answer 2

before的用法是什么

Answer 3

用在短语前是介词
用在句子前是连词

Answer 4

before 在。。。之前
介词prep.在…前
连词conj.在…以前
副词ad.以前
依具体情况而定