Last term our maths teacher set so difficult an examination problem _____ none of us worked it out. 

A. that    B. as    C. so that    D. which

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.

　 A. that 　 B. as    C. so that 　 D. which

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.

　 A. that 　 B. as   C. so that 　 D. which

Last term our maths teacher set so difficult an examination problem ______none of us worked out.

A. that      B. as     C. so that     D. which

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.

A. that 　 B. as 　 C. so that 　 D. which

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.

　 A. that 　 B. as

　 C. so that 　 D. which

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.

　 A. that 　 B. as C. so that 　 D. which

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.      A. that 　                 B. as                              C. so that 　                D. which

Last term our maths teacher set so difficult an examination problem ______none of us worked out.

A. that      B. as     C. so that     D. which

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.

A．that 　         B．as           C．so that 　       D．which