in that case与in which case的区别

问题描述

Of course it may rain, in _______ case we'll have to hold the ceremony indoors.
A. that      B. which
答案是 which，但为什么不能是 that 呢？查了词典，in that case 是一个固定搭配，意思是“如果那样的话”，好像从句意和搭配上看，选 that 都很通顺。但为什么非要选 which 呢？

老师答疑

曾老师：

注意标点符号。这是一个复合句，in which case…构成非限制性定语从句。如果空格里填that，那么Of course it may rain之后的逗号要改为句号，而且介词in也要大写（即：In thatcase）。比较：

She may have missed her train, in which case she won’t arrive for another hour. 她可能已误了火车，要是那样的话,再一小时她都不会到。（一个复合句）

He is said to be not at home. In that case, we shall not go there. 听说他不在家，那么我们不去了。（两个简单句）