英语语法精讲精练：第3讲 过去完成时
二、过去完成时的判断依据
1.由时间状语来判定
一般说来，各种时态都有特定的时间状语。与过去完成时连用的时间状语有：
（1）by +过去的时间点。如：
I had finished reading the novel by nine o'clock last night.
（2）by the end of +过去的时间点。如：
We had learned over two thousand English words by the end of last term.
（3）before +过去的时间点。如：
They had planted six hundred trees before last Wednesday.
