Question

be late for school的be是be的原型还是be动词？

Answer 1

这里的be是动词原形
be late for是一个短语，意思为迟到。

be late for翻译为上学迟到
希望我的解答能帮助你(=^ ^=)

Answer 2

be有am is are ，还有它的过去式和其他形式。be随主语和时态的变化而变化。
如：He is late for school.
I am late for school.
She was late for school yesterday.