---I can't work out this problem．

---__________．

1. A.
   Why don't you asking Kate for help?
2. B.
   Why not ask Kate for help?
3. C.
   How about ask Kate for help?
4. D.
   You'd better stop to do it．

I can't work out this problem It is ________ one. It's one of the most difficult problems I have ever met with.

A. the more difficult

B. the most difficult

C. a most difficult

D. a more difficult

A. the more difficult

B. the most difficult

C. a most difficult

D. a more difficult

—　　　　　　  

A. Why don’t you asking Kate for help?

B. Why not ask Kate for help?

C. How about ask Kate for help?

D. You’d better stop to do it.