1分别用for短语, since短语或从句造句 用现在完成时 2用that is why造句

I have been here for 3 years. for延续，加时间段。
I have been here since 2009. since加时间点。

that is why 是主语从句中的表语从句。That is why i come here.这就是我来这的原因。

1.They have studied here for over two years .
He has worked here for ten years .
We have been friends since for years ago .
Lucy has had her new walkman since she bought it three weeks ago .
2.That is why I came late .
That is why I dislike maths .

1，i have been there for a long time. i have been there since 1999
2.that is why i want to call on hhim

i have lived here for three years.
i have lived here since three years ago.
that is why i want to go home.