嗨，大家好！我們知道long的意思有「長久的，長期的」，tooth的意思是「牙齒」，那long in the tooth是什麼意思？
long in the tooth的意思是「to be old, often too old to do something」，即「年老，（常指）年紀太大（而無法做某事）」。
這句習語源於馬的牙齒。馬的年齡越老，其牙齒也就越長，因此看馬的牙齒就能得出馬的大致年齡。
在亨利·埃斯蒙德的《The History of Henry Esmond》中，首次用這個習語來描述人而不是馬：
His cousin was now of more than middle age, and had nobody's word but her own for the beauty which she said she once possessed. She was lean, and yellow, and long in the tooth; all the red and white in all the toy-shops in London could not make a beauty of her.
隨著時間的發展，這句習語通常用於描述某人年紀太大了。
例句：
He's a littlelong in the tooth to be wearing shorts, don't you think?
他年紀有些大，穿不了短褲了，你說是不是？
下面再介紹一個關於tooth的習語：cut a tooth
cut a tooth的意思是「to grow a new tooth」，即「出牙，長出新牙」。
例句如下：
Amy is cutting a tooth. That's why she's crying.
艾米正在長牙，難怪她哭個沒完。
以上就是今天所學內容，你學會了嗎？