[verb] + [preposition] + [object]
[verb] + [adverb] + [preposition] + [object]
Some verbs come with a small word like after, for or into, and the two words have one meaning together. With these verbs the object, even a short word like it or her, goes after the small word. You never put it in the middle.
With turn off you can say turn it off. With these verbs you can't. The pronoun goes at the end, like a noun.
Some have two small words: get on with (have a good relationship with someone), look forward to (feel happy about something that is coming), put up with (accept something bad without complaining), run out of (have none left). All three words stay together, and the object comes last.
After look forward to, a verb takes -ing, because to here is a preposition.
The object never goes between the verb and the small word, and a verb after look forward to is never the base form.