为什么所有的师范大学都翻译成nomal university normal 在这里怎么解释?

A normal school was a school created to train high school graduates to be teachers.Its purpose was to establish teaching standards or norms,hence its name.Most such schools are now called teachers' colleges; however,in some places,the term normal school is still used.
就是 师范大学 的意思

normal university 好像不是咱们说的师范大学，电视里记得演过。但具体怎么说，理由怎样我忘了。。。