He is sitting the classroom.A. at the frontB. in the front ofC. in frontD. in front of

问题补充：

He is sitting the classroom.

A. at the front

B. in the front of

C. in front

D. in front of

答案：

A. at the front

(答案→)B. in the front of

C. in front

D. in front of

解析：句意：他坐在教室的前面。in the front of在…前面，在范围之内的前部；in front of在…前面，在范围之外的前面。故选B