如果我精通XX怎么说?

I am good at

精通
acquire one’s mastery of
at home on
at home with on
at home with

精通于
be versed in

精通于
have a good command of

精通英语
have a good command of English

"If I master sth" or "If I'm good at..."
master指“精通”

My specialities/speciality are/is...

I'm good at...

be proficient in 精通于...

I am good at……我擅长……的意思