初中英语语法:初中语法总结之since和for

Since 用来说明动作起始时间，for用来说明动作延续时间长度。

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.

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、1980, last month, half past six）。例如：I have been here since 1989. 1989起，我一直在这儿。

2） since +一段时间+ ago。例如：I have been here since five months ago. 我在这儿，已经有五个月了。

3） since +从句。例如：Great changes have taken place since you left. 你走后，变化可大了。 Great changes have taken place since we were here. 我们走后，变化可大了。

4） It is +一段时间+ since从句。例如：It is two years since I became a postgraduate student. 我考上研究生有两年了。