[-C21] When the old man _____ to walk back to his house ,the sun _____ itself behind the

题目

[-C21] When the old man _____ to walk back to his house ,the sun _____ itself behind the
mountain.
A.was starting ; hid
B.had start ; had already hidden
C.had started ; was hiding
D.started ; had already hidden
翻译并分析,为什么选D不选B?

答案

翻译：当这个老人开始向家走的时候,太阳已经落山了.
首先B中 had start是不正确的,过去完成时为 had started
其次,过去完成时应用在有一个过去的时间点做参照的情况下,即一个过去时做时间点,才用过去完成时,表示在过去的时间点之前就已经发生.
D中,started用过去时,做过去的时间点