--What theywhen you got there Tom?--Sorry I forget.A. are; doingB. were; doingC. did; do

问题补充：

--What theywhen you got there, Tom?

--Sorry, I forget.

A. are; doing

B. were; doing

C. did; do

D. will; do

答案：

A. are; doing

(答案→)B. were; doing

C. did; do

D. will; do

解析：句意：当你到那儿时，他们正在做什么，汤姆？——抱歉，我忘了。结合语境可知上文描述的是过去某时正在做的动作，故用过去进行时态，选B。