He never is late for class.为何不对

never 作为频率副词和always,seldom,usually 等词一样,如果放在句子中间,要放在：
1.be 动词之后
如此句要说：
He is never be late for class.
2.助动词之后
I have never seen him before.
3.行为动词之前
上句的seen 是行为动词,这时 never 便置于助动词和行为动词之间