THE EXERCISE WAS SO DIFFICULT THAT WE COULDN’T DO IT.A. IT WAS SO...

37. The exercise was so difficult that we couldn’t do it.

A. It was so a difficult exercise that we couldn’t do it.

B. It was too a difficult exercise that we couldn’t do it.

C. It was enough a difficult exercise that we couldn’t do it.

D. It was such a difficult exercise that we couldn’t do it.