The letter ____three days ago and it ____yesterday.

问题描述:

The letter ____three days ago and it ____yesterday.
A.was posted,arrived
B.had been posted,was arrived

第一个空:信应该是被邮寄,所以用被动语态, 三天前,只能用过去式的被动语态,was posted.
第二个空arrive是不及物动词,不及物动词没有被动语态,所以选arrived.