Last week our maths teacher set so difficult an examination problem___ none of us worked out.A.thatB.whichC.as D.so that.Please explain.

问题描述:

Last week our maths teacher set so difficult an examination problem___ none of us worked out.
A.that
B.which
C.as
D.so that.
Please explain.

.......so........ as none of us worked out
.......so........ that none of us worked it out
as 引导定语从句,先行词在从句中充当成分,像。。。。那样
that 引导状语从句,如此。。。。以至于

A
SO.TAHT.句型