tempos

（4）以oo结尾的名词只加s。如：zoo-zoos.4、以“辅音字母 + y“ 结尾的名词，则先把y改成i，再加es。如：baby-babies, university-universities, fly-flies, impurity-impurities.5、 下列以f或fe结尾的名词，须先将f或fe改成v，再加es。这些名词是：calf, half , knife, leaf, life, lo...