有兩道時(shí)態(tài)題,我有點(diǎn)區(qū)分不了.

Our teacher _____for 10 years before she came here.

     A.taught B.had taught C.has taught D.had been taught 答案選B

  2.   Our new English teacher, who is said to have moved back to China, _______in America for almost    10 years.

        A lived B. has lived C. was living D.had lived 答案選A

還有好些的題目,都讓我有點(diǎn)無法辨別何時(shí)該用一般過去式,尤其是什么最后有for ...months/years 時(shí)間類型的.麻煩誰能給我仔細(xì)講解一下技巧什么的