Question

【题目】— Where's Mike?
— He is working _____ math _____ in the classroom.
A.in; problem
B.out; problem
C.in; problems
D.on; problems

Answer 1

【答案】D
【解析】考查动词短语。work on“从事于”；work out“算出，解决”；work不与in搭配使用。problem为可数名词，本题句意是 “Mike正在教室做数学题”，故 选D。