A. If you can instantly become an expert in anything, what would that be?

Frankly speaking, I would like to be an expert in English education field because my final goal is to speak fluently in English.

So, it would be a chance to know how to speak English fluently and effectively like a foreigner and to find out what part of skills in English I lack.

=> Corrected: The sentences are corrected grammatically.

=> Corrected spelling.

B. Make these sentences into English. (11/11/21)

-전 잡념이 많아요.

I have lots of trivial thoughts -> I have a lot of things going on in my mind

-상대팀 선수들이 우리보다 체격이 두 배로 커서 주눅이 들었어.

The physique of the opposite team's players was twice as big as ours, so I felt intimidated.

->The other team was twice our size so we were intimidated.

-촌스러워 보일 수 있어.

It might look tacky. -> It could look tacky.

=> Another way: Your sentences are okay and these are other ways of saying them.