题目内容：

______(turn) off the light before leave the classroon.空里填什么,解释

优质解答

Turn 这是一个祈使句,表示请求.祈使句要用动词原形.
另外：这个句子的正确写法有两种：
Turn off the lights before you leave the classroom.
Turn off the lights before leaving the classroom.