OK, here's the scoop on this usage:
Please consider the utterance (I'm working with speech here).
A) the repetition of the preposition (stranding the preposition) is not needed:
1) declarative: I'm going to New York later this afternoon.
2) interrogative: Where are you going later this afternoon?
Notice how the TO disappears in the question.
Ah, but then why do people say: Where are you going to [this afternoon]?
There are various answers. They are not educated speakers or they are sloppy speakers. The fact is that in the question to is not needed. That said, people do speak like that. Would a speaker like myself say it? Probably not. Except for emphasis: Where did you say you were going to?
Where are you going to?
Where to are you going?=not idiomatic or heard
To where are you going?=not idiomatic
1) Declarative: He is at the game? [standard];
2) Interrogative: Where is he? The preposition, as with to above, is not needed.
3) Where's he at? or Where is he at? [marked as uneducated or dialectal, as in Black English or common varieties where people aren't really paying attention to their own speech]
At where is he? = not idiomatic, not heard
B) stranded prepositions (aka hanging prepositions)
Let's start with a declarative sentence: I'm writing about horror movies.
Interrogative (standard speech): What are you writing about?
Not repeating the object of the preposition is called preposition stranding and it is very common in spoken English and is used by native English speakers. /About what are you writing/ though grammatical would never be heard, really.
1) Declarative: This depends on the student's attitude:
2) Interrogative: standard speech: What does this depend on? More of a written form: On what does this depend? But, it could be said.
The last example: For whom are you doing this? Can be stranded in standard speech: Whom are you doing this for? Please note also that here /who/ is often used in place of /whom/ and is acceptable in some circles, but not in formal speech. However, the stranded preposition is fine.
According to Cambridge Dictionary here and here:
be up to sth = to be doing something:
- What are you up to at the moment?
and
get up to sth = to do something, often something that other people would disapprove of:
- She's been getting up to all sorts of mischief lately.
- I wonder what those two got up to yesterday?
So the use of to get up to sth implies a bad intention / deed, unlike to be up to sth.
@RonaldSole correctly adds in the comment (thank you):
to be up to sth = is also used in the sense of be capable of.
- Will he be up to a long walk so soon after his operation?
Best Answer
Do you interest something? is a perfectly grammatical sentence. It often doesn't make much sense, but that's simply because of the meaning of the verb interest.
https://www.merriam-webster.com/dictionary/interest
So, I interest him means I make him interested. That's a grammatical and sensible sentence. I interest rock music is grammatical, but since rock music doesn't have any feelings, it doesn't make sense to suggest that rock music could be made interested in me.
This is no different than many other transitive verbs.
Consider: I paint the house as compared to the house paints me.
In some other languages, the object of the sentence would be marked somehow, making the word order more flexible, allowing sentences like:
I paint the house-object and the house-object paint I.
But since English has such a limited case system, we rely more heavily on word order. The subject tends to precede the verb, which tends to be followed by the object.