This problem is so difficult that ________ students can work it out.

[　　]

This Maths problem is so difficult that only __________ students can work it out．

　　A．a few　　B．few　　C．a little D．little

This math problem is so difficult that only ________ students can work it out.

[　　]

 This is _______ difficult problem that few students can work it out.

A. so                     B. so a                      C. such                     D. such a    

This is______difficult problem that few students can work it out.

A.so B.so a C.such D.such a