—You were not listening；what troubled you?
—I my ing math exam．
A. am thinking about
B. was thinking about
C. had thought about
D. will think about
网友回答
A. am thinking about
(答案→)B. was thinking about
C. had thought about
D. will think about
解析：考查时态.句意:你没有在听.什么困扰你了?我正在想来临的数学考试。可知答语中叙述的是过去（刚才没有听时）的动作，故用过去进行时态，选B。