No. He sat by the window is correct. He sits by the window is the correct use of sit.
Their house is over there; they're not there.
Yes. Example sentence: We could hear the bees buzzing outside our window.
Mary Jane loved to sit in her window, in the reading nook her father built for her, and read her favourite books.
"How are you" is a correct sentence.
Its problem is not grammatical, but idiomatic. We say take an exam, or sit for an exam, but we do not say attend an exam. A sentence may be grammatically correct and still wrong.
"Would you prefer the window seat?"
Since "whom" is the subject of the sentence, it should be "who" not "whom."And you need some sort of noun after "the."For example:Who is displayed in the window?If you want an example of how to use the word "whom," we need to change the sentence around:Whom did they display in the window?In this example, the subject is "they" and the object is "whom." So "whom" and not "who" should be used.
You can't answer this without the rest of the sentence. "He and his friend came to see me; I asked him and his friend to sit down." is an example of correct usage.
Yes, this sentence is correct.
You can sit here. What is the naming part of the sentance?
It could be either. 'Sit!' as an imperative form of the verb to sit (an instruction given to a dog, for example) is a sentence in its own right. Sit can also be just one word in a sentence, for example 'I asked you not to sit there.' In that case it would be a fragment.
You are palpitating. This is a correct sentence.