Do you own a computer? Grammatically it makes sense as a question. You do own a computer would be a suitable answer.
Work at the computer isn't correct language. But, work on the computer isn't a complete sentence. She/he is working on the computer, is correct. But of those two, option 2 would be fine.
no it is not a correct sentence.
Computer nerd is the correct term.
This is not a sentence it is a phrase and as a phrase it is correct.
The sentence, "They are going to the beach." is correct.
The correct sentence is He is allowed to do it on his own.
You already own a bicycle.
I can only guess at what you are trying to say, but I guess that this sentence should have been, understand it in your own home. You don't have to go to school to learn about this; you can understand it in your own home.
"The dog has its own collar" is grammatically correct. Many people mistakenly use "it's" in this kind of sentence, but that is the contraction for "it is," not the possessive form of "it."
Work at the computer isn't correct language. But, work on the computer isn't a complete sentence. She/he is working on the computer, is correct. But of those two, option 2 would be fine.
He set the computer into the correct mode and then it worked perfectly.
No. It would be "A new computer was placed in her room," "A new computer was brought into her room," or some derivative.
No. This is a clause that cannot stand on its own. It is not a complete sentence. A sentence needs a subject and a verb.
Yes, I can: I didn't get a ride, I got here on my own.
Is 'going to' or 'will' correct in the following sentence: 'As soon as I arrive home, I am going to switch on my computer' ? Thank you
"How are you" is a correct sentence.
Yes, this sentence is correct.