可不可以理解 英语中状语就是修饰谓语动词的.如果不可以,请问为什么?

可不可以理解 英语中状语就是修饰谓语动词的.如果不可以,请问为什么?
最好能举例说明,
比如这句话中
He helped popularize the idea that some diseases not previously thought to have a bacterial cause were actually infections,which aroused much controversy when it was first suggested.
最后的when it was first suggested 作状语是怎样修饰谓语动词的呢？