這句本來就是賓語從句,什么樣的話題（subject）,他們正在討論的（they are discussing）,所以按照你的這個解釋,that在這里引導賓語從句是可以省的.可以直接改為“he always makes his student's interested in any t...anything作interested in的賓語，topic作discussing的賓語，that又不是賓語，為什么能省略？topic應該是作為整個句子的賓語成份，“使他的學生對topic感興趣”，而they are discussing作為從句修飾的就是topic，這里that作為賓語從句的引導詞，一般情況是可以省略的。 trust me 你這里不能這樣理anything作interested in的賓語，topic作discussing的賓語。make sb interested in 是動詞短語，是某人對什么感興趣，topic是整句的賓語。 還有確切的說whatever=any topic that 或者anything that 所以要么改為：makes his student's interested in any topic （that） they are discussing. 或者makes his student's interested in anything（that） they are discussing.