polish up例句

Polish up your writing skills on a one-week professional course.
上为期一周的专业课，提高你的写作技能。

I'm going to New York, so I must polish up my English.
我要去纽约, 因此我必须提高英语水平.

You've got to polish up on your idiomatic expressions.
你需要改善和提高你的惯用语表达能力.