沒(méi)有 fifteen year old 與,fifteen-years-old,這兩種用法 ,即它們的書(shū)寫(xiě)是錯(cuò)誤的.fifteen-year - old 15歲的（ 相當(dāng)于形容詞,后要接名詞）fifteen years old 只能作表語(yǔ).如The boy is fifteen years old .= He is a ...fifteen years old是15歲，例如I am fifteen years old，而fifteen-year-old是十五歲大，例如my brother fiftten-year-old，而fifteen-years-old是指十五歲大的，例如fifteen-years-old should be allowed to do homework with friends記?。?數(shù)字與名詞組成的復(fù)合形容詞用‘ -’ 連接，名詞不能加S， 這類形容詞后面要接名詞

要注意中英文用法上的區(qū)別。