His constant apple-polishing of the teacher makes other students uncomfortable.

apple-polishing 是由 apple（苹果）和 polishing（擦亮）组成的复合词。polishing 是动词 polish（擦亮、抛光）的现在分词形式。 apple-polishing 字面意思是"擦亮苹果"，引申为"讨好、奉承"，源自学生给老师送擦亮的苹果以讨好老师的传统。这个短语指通过奉承或讨好来博取他人好感的行径。