Sentence Correction

"We want the teacher to be he who has the best rapport with the students."

why "he" has to be after "be" - that's what it says in the answer, but i dont understand. Kindly explain please thanks.

well you have to look at the differences between whom and who.
If you can restate the sentence in your head and say HIM ..that sentence can hold a WHOM.. Because both terms (him and whom) are possesive.

then you have HE and that is paired with WHO. Again, if you can substitute he into the sentence when referencing t the person you can use who. non possessive ..

so you now have he who in you sentence.. and you wouldn't be able to say he whom..