A. a;/                           B. the; a                       C. the; the                    D. /;a

2．Let’s learn to use the problem we are facing _____ a stepping stone to future success.

A. to                            B. for                           C.as                     D.by

3. It’s quite _______ me why such things have been allowed to happen.

A. for                           B. behind                    C. against                      D. beyond