题目内容：

Teacher in front of blackboard 的in front of 可以换成before么

优质解答

in front of 强调位置上在...之前,before 强调时间上在...之不可以的at or in the front[同] in front,ahead,before[例] I see the lights of a town aheadthe road ahead is foggystaring straight aheadwe couldn'...