by和before用法有什么不同都指在时间上的俄

by和before用法有什么不同都指在时间上的俄
by和before用法有什么不同
都指在时间上的俄

by和before用法有什么不同都指在时间上的俄
by是截止到什么时间
before是.时间以前
差不多的
反对上楼的
by可以用在一般现在时
英语课本上就有原句
before也可以用在过去时态,过去完成时...

by 在句子中时主句要用完成时。
用befoer时，主句一般为一般时。

BY
作介词prep.
1. 被,由
The homework was assigned by the teacher.
这些家庭作业是老师布置的。
2. 靠,用,通过
They crossed the river by ferry.
他们乘渡船过了河。
3. 经由;沿
Ellen flew to Chicago by way...

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BY
作介词prep.
1. 被,由
The homework was assigned by the teacher.
这些家庭作业是老师布置的。
2. 靠,用,通过
They crossed the river by ferry.
他们乘渡船过了河。
3. 经由;沿
Ellen flew to Chicago by way of Minneapolis.
艾伦经由明尼阿波利斯飞往芝加哥。
4. 在...旁边,靠近;在...手边
I haven't got any money by me.
我身边没有带钱。
5. 不迟于;在...之前
We had to get there by evening.
我们必须在夜晚前抵达那里。
6. 根据,按照
How do you know he didn't act by the rules?
你怎么知道他没有按规定行事?
7. (表程度)相差
He missed the bus by three minutes.
他晚了三分钟没赶上那班公车。
8. 凭,对...(发誓)
I swear by God!
我对上帝发誓!
9. (乘除法上)以...,用...(乘或除)
Nine divided by three makes three.
九除以三得三。
10. 以...计,按
You'll be paid by the hour.
你的工资将按时计酬。
11. 在...的时候
He had to sleep by day and work by night.
他只好白天睡觉,晚上工作。
12. 就...来说,关于
Philip is a doctor by profession.
菲利浦的职业是医生。
13. (表连续或反复)逐个;逐批
The teacher explained the text sentence by sentence.
教师逐句讲解了这篇课文。
14. 由于
She took my umbrella by mistake.
她误拿了我的伞。
作形容词 ad.
1. 经过;过去
A truck went by.
一辆卡车开过。
2. 在旁边
When I filled out the form she was standing by all the time.
我填写表格时,她一直站在我身旁。
3. (放)在一边
They put money by for later use.
他们储存钱以备将来使用。
BEFORE
作介词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。
作形容词 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。
作连词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。
由以上，看出by的第5，11条，于before的第1，2条可作比较
并且，before多了连词的功能
建议，这类虚词，要结合例句理解
尽力回答了，希望答案您能满意。

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