—What class are they having?—Math. Their math teacher is the classroom. A. in the front o

问题补充：

—What class are they having?

—Math. Their math teacher is the classroom.

A. in the front of

B. in front of

C. on

D. behind

答案：

(答案→)A. in the front of

B. in front of

C. on

D. behind

解析：in the front of在……的前部；in front of在……前面；on在……上面；behind在……后面。句意：他们正在上什么课？——数学。他们的数学老师在教室前部。结合语境可知选A。