嘴巴的复数形式是 mouths。
这个词来源于古英语 "mǣð"，在中世纪英语中变成了 "mǣþ"，最终在现代英语中变成了 "mouth"。
例句：
The crocodile has very sharp teeth in its four mouths. (鳄鱼有四张嘴巴，里面有非常锋利的牙齿。)
The baby was fed with a bottle and it's mother's mouth. (婴儿用瓶喂养，也用妈妈的嘴巴喂养。)
The doctors couldn't find any sign of injury in the patient's mouth. (医生们在病人的嘴巴里没有发现任何受伤的迹象。)