译林版《牛津高中英语》 (模块三•高一下学期) (2007年12月第4次印刷) p10：In most cases, we cannot use that to begin a noun clause after a preposition. However, we can use that to begin a noun clause after in or except.

The problem lies in that the mist may become a thick fog.

众所周知，在英语中，in that 已经形成一种固定搭配，即《牛津高阶英语词典》所说的Idioms (习惯用语) ，且有了固定的含义“for the reason that；because (因为) ”。 

L G Alexander 等在其 编著的English grammatical structure (Second impression 1977) p197上把in that定义为Subordinating Conjunction，并举例：We have failed in that some of you remain unconvinced.

Randolph Quirk等在其编著的A COMPREHENSIVE GRAMMAR OF THE ENGLISH LANGUAGE (First printed1985) P998上将in that定义为Complex Subordinator (即复合从属连词) 。

John Sinclair在其主编的《Collins Cobuild 英语语法系列》：9 《连词》 ( 任绍曾主编 外文出版社 2001年4月第1版) p44上把 in that 定义为引导“理由从句”的 “连接词”：I am an optimist in that I believe that human beings do not always perversely try to make life worse for themselves. 我是乐天派的人，因为我认为人类并非总是违反常情地力图使自己的生活变差。

Most of them are not in reality engineers, in that the work they do is mostly clerical. 他们中的大多数人实际上都不是工程师，因为他们做的主要是办公室工作。

再请看其他的例证：

1. Lingoes (http://www.lingoes.cn/) 之“柯林斯高级英语学习词典” (第5版) ：You use in that to introduce an explanation of a statement you have just made.   I'm lucky in that I've got four sisters.

2. Lingoes (http://www.lingoes.cn/) 之“美国传统词典[双解]”：习惯用语: in that ― for the reason that. 因为

3. Lingoes (http://www.lingoes.cn/) 之 “朗文当代英语词典”：in that ―used after a statement to begin to explain in what way it is true：I've been lucky in that I have never had to worry about money.

4. Lingoes (http://www.lingoes.cn/) 之“麦克米兰英语词典