Question

since和for的区别怎么区分since和for，各自用

Answer 1

Since 和for区别

1，Since +时间点，具体时间

“自从、、、、以来，从、、、以后” 用来说明动作起始时间

I have been in Beijing since 2010.

2，For + 时间段，用来说明动作延续时间长度，因此句中的谓语动词，也应该是延续性动词。

I have been in Beijing for one year。

We have learnt English for about three years.

I have been here for 3 days. (对)

I have arrived here for 3 days.（误）
一，since 的四种用法

1，since + 过去一个时间点（如具体的年、月、日期、钟点、ago. 1990 , last month , half past six

I have been here since 1990. 1990起，我一直在这儿。

2，since+ 一段时间+ago

I have been here since five months ago。自从五个月前，我已经在这儿了。

3，since+从句Great

Changes have taken place since you left. 自从你走后，已经发生了很大的变化。

4，It is +一段时间+since从句

It is two years since I became an English teacher. 我成为英语老师有两年了。

Answer 2

二者做连词，表示原因时
since的语气比for要强
例句：
Since we were in the area, we'd stop by and see them.
既然到了这个地方，就该顺便去看看他们。
We listened eagerly, for he brought news of our families. 我们急不可待地听着，因为他带来了我们家人的消息。

Answer 3

二者有两种类似用法，即都以构成时间状语或原因状语。
一、作时间状语时的区别
since后面说的是一个时间“点”，比如1978，某年某月某日，某时某刻……

追答

而for的后面则是“一段”时间，two years, one week, 9 hours……
二、作原因状语时，二者用法差不多，都用于表述不很强烈的原因（非直到因果关系）。