問：英文報紙有以下一句：Summer language tours put children in a fun environment to brush up on their English skills, and, at the same time, expand their horizons and become more independent。那brush up on的on字，是不是應刪去？Become more independent是不是應改為make them more independent？
答：讀者示下那一句，應是說「暑期語文學習遊，使孩子身處有趣的環境之中，學習英文，同時增廣見聞，並變得較為獨立」。Brush up (something)或作brush up on (something)，那on不必刪去；不過，這動詞片語（phrasal verb）一般是指「溫習（荒疏了的技能）」，即牛津成語詞典 Oxford Dictionary of Current Idiomatic English 所謂revise or practise a skill in order to be proficient in it once again。香港學生去外國旅遊，學習英文，用learn English或improve their English應比brush up (on) their English (skills)貼切一點。
至於become more independent三字，明顯是因句子太長，以致作者忘了句子主詞（subject）是summer language tours，不是children。你可以說Summer language tours put children in a fun environment... to expand their horizons，卻不能說Summer language tours put children in a fun environment... to become more independent，因為這似是說「暑期語文學習遊要變得較為獨立」。讀者提議的改寫法很對。另一寫法是：Summer language tours help children to improve their English in a fun environment, and, at the same time, expand their horizons and become more independent.