问题详情

Which "which" in the following sentences CANNOT be replaced by "as"？
A．Jane decided to quit her job, which we all knew.
B．Our boss invited us to dinner, which was very kind of him.
C．He changed his mind so frequently, which made me quite angry.
D．He is a teacher which is clear from his manner.请帮忙给出正确答案和分析，谢谢！