---I have great difficulty working out this problem.

--- ______ to me, you ______ less difficulty with such problems now.

1. A.
   If you had listened; would have had
2. B.
   If you listened; would have
3. C.
   Had you listened; would have
4. D.
   If you listen; will have

--I have great difficulty working out this problem.

-- ______ to me, you ______ less difficulty with such problems now.

[　　]

A．If you had listened; would have had

B．If you listened; would have

C．Had you listened; would have

D．If you listen; will have