be sharp at 基本例句 擅长; 精于 She is good at designing eye-catching packages.她擅长设计花俏的包装。 Be sure to turn off all the lights when you leave.他擅长写作。 Tom is a great hand at painting.汤姆精于绘画。 After reading this book, you will be proficient in writing.读完这本书，你会精于写作。