polish up什么意思解释？

polish up的音标：polish up的英式发音音标为：['pɔliʃ ʌp]polish up的美式发音音标为：['pɑlɪʃ ʌp]...

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....