问题详情

Which of the following contains an adverbial clause of concession？

A．I can learn while I work.

B．I"m in an awkward position, in that he"s not arriving until tomorrow.

C．Late as it was, they continued to study.

D．He made for the door directly he heard the knock.

请帮忙给出正确答案和分析，谢谢！