Catherine ________ the letter before her mother came into her bedroom.
A.has written
B.was written
C.had written
D.is writing
网友回答
C解析剖析：此题主要考查动词的时态。依据后面的her mother came into her bedroom可知时间是过去，故可以排除A和D；B是被动语态，而此题为主动语态，故B也可以排除掉；由题意可知，Catherine是在妈妈进来之前写的，而妈妈进来的动作came into是一个过去的动作，故Catherine的动作为“过去的过去”，也就是说此题为过去完成时态，故