—I thought you for vacation tomorrow. —I had planned to but I have a very important mee

问题补充：

—I thought you for vacation tomorrow.

—I had planned to, but I have a very important meeting to attend tomorrow.

A. will leave

B. are leaving

C. have left

D. were leaving

答案：

A. will leave

B. are leaving

C. have left

(答案→)D. were leaving

解析：本题考察的是进行时表示将来时的用法。进行时表示将来时的时候，所使用的动词必须是表示位置变化的动词，同时这件事情必须是事先计划好的。句义：—我以为你明天会去度假的。—我本来是这样计划的，但是明天我有很重要的会议要参加。这正是事先计划好的事情。本句使用的是过去进行时表示过去将来时。故D正确。