加逗号就行:这个叫做非限制性定语从句。
如:
The man, whose brother is in the army, is my teacher.
加句号不行。因为加了句号就不是定语从句了。
当先行词为前面的整个句子时,非限制性定语从句的关系代词用as。as引导的非限制性定语从句可以置句首、句中、句尾。如: China is famous for the Great Wall, as is well known. As we all know , China is famous for the Great Wall. China, as we all know , is famous for the Great Wall. 当先行词为same、such或者先行词被这两个词修饰时,后面的定语从句用as.如: This knife is the same (knife) as I saw that day. I've never heard such (stories) as he tells.