preposition placement

[Gregory_E_V]

Which one is correct:
Shall I turn the lights on?
or
Shall I turn on the lights?

[Tdol]

They're both fine. If you replace 'the lights' with 'them', then it must come ater the verb:

Turn on the lights
Turn the lights on
Turn them on

[Gregory_E_V]

Thanks a lot
By the way,
'Turn on them'
is not correct?

[Casiopea]

That's right. *Turn on them (the lights) is ungrammatical. Pronouns don't work in that structure. But if it's a phrasal verb, like turn on, as in to attack somebody, then the pronoun works. Like this,

Don't turn on (attack) them. grammatical
Don't turn on them (the lights). ungrammatical

[Gregory_E_V]

Thank you very much, Casiopea. Your explanation is very clear and useful.
Your web site is really great, I enjoy it.
My best regards.

[Casiopea]

You are most welcome, Gregory.