— Why didn’t they complete the task in time?— Because it was not until late afternoon the

问题补充：

— Why didn’t they complete 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

答案：

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。