You can’t imagine what great trouble they have the problem .A. to solve; being talked ab

问题补充：

You can’t imagine what great trouble they have the problem .

A. to solve; being talked about

B. solving; discussing

C. to solve; to talk about

D. solving; being discussed

答案：

A. to solve; being talked about

B. solving; discussing

C. to solve; to talk about

(答案→)D. solving; being discussed

解析：由have great trouble （in）doing sth.可知第一空应用solving; being discussed作定语修饰problem，表示“正在被讨论的问题”。