Question

现在完成时中since和for的区别，各举一个例句

Answer 1

since表示动作的起始时间，for可以表示动作延续时间的长度。
例如：I have lived here for more than twenty years.(我在这儿住了二十多年了）
I have lived here since I was born.(我从出生起就住在这儿了）

Answer 2

I have been here since when I was 8.我从8岁开始就在这里了。
I have been here for 8 years. 我已经在这里呆了8年了。
还是要回到单词的原意上，since：从---开始计算 for：持续了多久。，

Answer 3

OR +时间段
SINCE +表示过去的时间点/ 从句.如
He has worked for two hours .
He has worked since two hours ago.