在什么情况下f和fe结尾的词汇要将f改为v,在加es?

a．一般情况下,直接加-s,如：book-books,bag-bags,cat-cats,bed-beds
b．以s.x.sh.ch结尾,加-es,如：bus-buses,box-boxes,brush-brushes,watch-watches
c．以“辅音字母+y”结尾,变y为i,再加-es,如：family-families,strawberry-strawberries
d．以“f或fe”结尾,变f或fe为v,再加-es,如：knife-knives
e．不规则名词复数：man-men,woman-women,policeman-policemen,policewoman-policewomen,mouse-mice child-children foot-feet ,.tooth-teeth fish-fish,people-people,Chinese-Chinese,Japanese-Japanese