关于现在完成时的用法（英语）-HowlonghaveyoulivedinBeijing?-twoyearsago.A.ForB.SinceC.AboutD./（为什么选B.since,而不是A.For）

Question

关于现在完成时的用法（英语）
-How long have you lived in Beijing?
-_________two years ago.
A.For B.Since C.About D./
（为什么选B.since,而不是A.For ）

Answer 1

for 后面跟段时间 I have lived in BJ for two years.我在北京住了两年了.
since后面跟过去一点 I have lived in BJ since two years ago.我从两年前就在北京住了.