Dobrý den.

Na jednom fóru jsem našel:

1)

With which book should I start? Which book should I start with? Both are correct, the former being the more formal of the two.

Opravdu lze začít s “with” – kvůli formálnosti? S tím jsem se nikdy nesetkal, je to opravdu tak? Já to považoval za chybu!

2)

Normally a speaker would simply choose a wording with which he or she felt comfortable.

Já bych řekl: Normally a speaker would simply choose a wording (which) he or she felt comfortable with. Osobně bych si myslel, že původní věta je špatně. Je?

3)

“And she formed bonds with her reasonable and low-key roommates, which might be expected, considering the reverence with which the concept of family is discussed among them.”

Zde bych také čekal “with” na konci věty.

Jde o to, že rodiloš udělal chybu a nebo mi zde něco uniká a věty jsou v pořádku? Budu moc rád za pomoc, docela mě to znejistilo. Chápu, že se nemohu spoléhat na to co najdu na internetu, ale zde se nejedná o jeden příklad.........

Ano, ve formálních textech se to takto někdy používá (ne nutně vždy) a je to zcela správně. V běžném hovoru ale dávejte předložku na konec.

Swan:
In a more formal style, a preposition is often put earlier in questions and relative structures, before the question word or relative pronoun.
With whom did she go?
It was the house about which he had told them.
She was the only person with whom he could discuss his problems.

This can also happen in infinitive complements, in a very formal style. A relative pronoun is used.
She needs other children with whom to play.
It is a boring place in which to live.
Note that after prepositions which and whom can be used, but not normally who and that.

Even in a very formal style, prepositions are not often put at the beginning of questions which have be as the main verb.
Who is it for, madam? (not For whom is it?)
And the structures where … to, what … like and what … for have a fixed order.
Where shall I send it to? (but not To where shall I send it?)
What does she look like? (but not Like what does she look?)
What did you buy that for? (but not For what did you buy that?)

Prepositions cannot be moved away from passive verbs even in a formal style.
In my family, money was never spoken about. (not … about money was never spoken.)