I'm a freshman at university. / I'm a first-year university student. I'm a freshman at university. / I'm a first-year university student.

What you wrote is okay, but I changed it to sound a bit more natural. You could use either of the options I gave you.

I'm a freshman in university student. I'm a freshman in university.

We can't go to the university anymore (because of COVID-19). We can't go to the university anymore (because of COVID-19).

I have to study for usinguse my PC to do my homework, but I'm not good at using PCit. I have to use my PC to do my homework, but I'm not good at using it.

I have to study for using PCuse my computer to do my homework, but I'm not good at using PCthe computer. I have to use my computer to do my homework, but I'm not good at using the computer.

I have to open my PC every day because I need to check indnotifications from my university. I have to open my PC every day because I need to check notifications from my university.

"Open" is fine if it's a laptop computer. If it's a desktop computer, then "turn on" or "use" is more appropriate.

I have to open my PCturn on my computer every day because I need to check indicfor information from my university. I have to turn on my computer every day because I need to check for information from my university.

It is difficult for me to answer the questions. It is difficult for me to answer the questions.

It is difficult for me to answer the questions. It is difficult for me to answer the questions.

Whenever I see the check my emails, I wasfeel afraid and sad. Whenever I check my emails, I feel afraid and sad.

Whenever I see the look at my emails, I wasbecome afraid and sad. Whenever I look at my emails, I become afraid and sad.

When we caI hope my English will level up before we return gto university, I wish my English skill is level up!. / I hope I can level up my English before we return to university. I hope my English will level up before we return to university. / I hope I can level up my English before we return to university.

When we can goBy the time we can return to our university, I wishhope my English skill iss can level up! By the time we can return to our university, I hope my English skills can level up!

I want to study English hard until finishthe end of the coronavirus. I want to study English hard until the end of the coronavirus.

I want to study English hard until finish coronavirusthe end of the pandemic. I want to study English hard until the end of the pandemic.

More natural to say "I want to study English properly until this whole pandemic is over."

I want to study English hard until finishthe end of the coronavirus situation. I want to study English hard until the end of the coronavirus situation.

Of course, until II want to speak English fluently. Of course, I want to speak English fluently.

Of course, until I speak EnglishAnd after obviously, until I'm fluently. And after obviously, until I'm fluent

Add obviously to sound more natural. Of course is fine as well though. You don't need to repeat "English" because it's assumed that's what you're talking about.

Of course, I will study until I can speak English fluently. Of course, I will study until I can speak English fluently.