four-fifths。四用基数词，五用序数词，基数词超过一，序数词后加s。
four fifthes 如果我的回答对您有帮助，请点击下面的“选为满意答案”按钮，谢谢您！
五用序数词。四用基数词，序数词后加s，基数词超过一four-fifths
fourth five
