It was not until they got stuck in the mud _____ they found their car ran out of gas.

问题描述:

It was not until they got stuck in the mud _____ they found their car ran out of gas.
A .before
B .when
C .so that
D .that

D that
这是一个强调句式,强调句式的结构是:it is (was) 被强调部分 that 其余部分