Have you realized the difficulty we have the problem?
A. worked out
B. to work out
C. work out
D. working out
网友回答
A. worked out
B. to work out
C. work out
(答案→)D. working out
解析：考查固定句型。have difficulty/trouble (in) doing sth.“做某事有困难”。句意“你意识到我们在解决这个问题时，遇到的困难吗？”根据固定句型可知，选D。