完成时since和for的用法,要求简洁易懂.不要发一大堆例:These foreign students have lived in China for two years.These foreign students have lived in China since two years ago.
问题描述：
完成时since和for的用法,要求简洁易懂.不要发一大堆
例:
These foreign students have lived in China for two years.
These foreign students have lived in China since two years ago.
答
since 是从什么时候开始前调几年以前
而for强调对现在的结果 since强调两年前住的现在住没住我们不知到的 for强调住这有两年时间了
答
Scine用在完成时时,后加时间点,而for后则加时间段!