____ is often the cases in other countries

Question

The British are not familiar with other cultures ,( )is often the case in other countries
括号选填as能理解，那which到底哪里错了？

Answer 1

这两个都是关系代词引导定语从句，都是代替整个主句，但是它们有以下两个区别。
as + be + 名词，如as is often the case就是一个，意思是，情况往往是这样。
as + be + 过去分词，如as is reported 正如报导的一样。
以上两个例子说明as后可接be 但是which 不可以，但which 有以下和as不同的用法。它后面的从句可以是肯定句也可是否定句，但as后的从句必需是肯定句。如
Tom came late again, which didn't surprise us .
He passed the exam, which made his parents happy.另外，which从句只在主句后。as从句可在主句前也可在主句后。

Answer 2

as is often the case （ 事情常常是这样的，常是如此} 这是固定用法 因此这里必须用as ，而不能用which本回答被提问者采纳

Answer 3

这里的先行词是The British ，而不是修饰前面整个句子滴追问

我觉得就是修饰整个句子没错丫