Question

since和for的区别

Answer 1

Since 用来说明动作起始时间，后面跟时间点 for用来说明动作延续时间长度。加一段时间
例如：
I have lived here for more than twenty years.我住在这儿二十多年了。
I have lived here since I was born. 我从出生起就住在这儿了。

注意：并非有for 作为时间状语的句子都用现在完成时。
I worked here for more than twenty years. （我现在已不在这里工作。）
I have worked here for many years.（现在我仍在这里工作。）

注意：用句型转换的方法，很容易排除非延续动词在有for/since结构的完成时中的误用。

1）（对） Tom has studied Russian for three years. = Tom began to study Russian three years ago, and is still studying it now.
2）（错） Harry has got married for six years. = Harry began to get married six years ago, and is still getting married now.
显然，第二句不对，它应改为 Harry got married six years ago. 或 Harry has been married for six years.

Answer 2

相同：都用于现在完成时
不同：since后加句子（S+瞬间动词），前面是现在完成时；for后加段时间，前面是延续性动词（现在分词形式）举例：I had learned english since i was very young.（我很小的时候就开始学英语了） I had learned english for 10 years.（我学英语已经10 年了）

Answer 3