— Why didn’t they plete the task in time?
— Because it was not until late afternoon they began to solve the major problem．
A. when
B. that
C. before
D. which
网友回答
A. when
(答案→)B. that
C. before
D. which
解析：考查强调句型。此题是一个含有not until 的强调句型，其结构为：it is/was + not until +其它+ that,下一个句子意思为：因为就是在下午晚些时候他们开始解决这个主要的问题。所以选B。