single out 是成语. single out 意味着（基于性别,种族,成绩,或其他因素）选出给予特别对待,重点是特别对待, 而 pick out 只有挑选的意思： 例： Mary was not just picked out from a group of students to be class prefect.She was singled out for her outstanding performance. Jane was always singled out for special treatment because she is the prettiest in the class.
