for\since\ago的区别

FOR

基本区别点：

1. 用在一段时间之前。

例子：

1. for 10 minutes
2. for 5 years
3. You've been waiting here for years.

SINCE

基本区别点：

1. 用在特定时间点之前。

例子：

1. since winter
2. since last night
3. They've been studying since 2018.

AGO

基本区别点：

1. 指向动作或改变发生时的那个点。
2. 可以和“since‘连用。

例子：

1. 3 years ago
2. 5 minutes ago
3. since 3 years ago
4. They've been dating since about 2 weeks ago.