Active to Passive voice: "School classmates make the best friends"

Question

Recently I've encountered one problem which I couldn't solve myself. I have a sentence, "school classmates make the best friends", and I want to rewrite it using the passive voice. However, after rewriting the sentence I am left with a few doubts.

Firstly, if I try to use the construction "are made by" (e.g. "The best friends are made by school classmates"), it sounds somewhat funny, therefore not unuseful - to me, at least. I think that the construction "are made by" is proper only in sentences, in which the predicate meaning is close to "are manufactured by" (e.g. "Wooden doors are manufactured by workers" and so on). The same, in my opinion, goes for "are made from" (e.g. "The best friends are made from school classmates" and "tubes made from plastic"). Is that true, or is it only my vision of the problem and is it possible to rewrite the sentence with one of these constructions ?

Secondly, if I try to use this other construction, "are made at" (e.g. "The best friends are made at school"), it seems somewhat closer to the meaning of the sentence in the active voice (refreshing our memory: "School classmates make the best friends"), but... I don't know, this sounds like we are talking about the plain meaning of "make" again, that is, as the verb meaning "to create".

Finally, the best way to rewrite the sentence which I could find is "The best friends are obtained at school classes". But is it possible to rewrite the sentence using passive voice and some form of "make" verb? The main problem here, I think, is an existence of a collocation "make friends", which interferes with regular contextual usage of "made by", "made at", "made from" and so on.

Thanks in advance for reading and answering!

Answer 1

The problem is that your make functions as a linking verb. Similar to become, it's a "resulting" copular verb.

School classmates make the best friends.

School classmates become the best friends

That is, school classmates equal (through process) best friends. Linking verb sentences are neither active nor passive, so there is no change to be made.

Your example here is indeed passive:

Passive: The best friends are made at school [by people].

Active: People make the best friends at school.

But that is a different (and transitive) sense of make: acquire.

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See also make, definition 11, at Longman.

Answer 2

No, neither of "The best friends are made by school classmates" and "The best friends are made from school classmates" will do and that is not a matter of using a preposition rather than another: it's just not idiomatic from the point of view of the possible meanings of "make".

"The best friends are made at school (classes)." is not better.

The reason is that "make" is a linking verb in this context (OALD, 13).

ref.

It follows that "make" can't be used that way.

What you might choose to say is "The best friends are to be made at school (classes)."; it comes to the same idea found in "school classmates make the best friends", to wit, circumstances are such that you'll count your best friends amongst school classmates.