高中英语动词时态语态一题
Afterclass,thestudentwentoutoftheclassroomonebyone,butonlyMary_____.
A.leftB.hadleftC.wasleavingD.wasleft
它的答案是A,我就奇怪为什么不能选D?干嘛非要用省略?与only有关么?