he buys a new car every year.she empties basket every day.两句中的动词+S为什么不一样?

y前是元音字母直接加s
前是辅音字母去y加ies

buy 的结尾y前面是元音字母u所以第三人称直接+s 后一个动词原形是empty 结尾y前是辅音字母，所以第三人称要变y为i 再加es

动词第三人称单数的变化规则
1、直接在动词后+s
like- likes play-plays
2、以s,x,sh,ch,接尾的动词：+es
wash-washes
3、以辅音+o接尾的动词：+es
go-goes
4、以辅音+y接尾的动词：变y为i+es
fly-flies
动词短语：
+s:Plays,skips,sings,gives,starts,likes,
buys some toys,gets up comes back home
makes noodles,eats lunch drinks coffee
begins his class ,practises the piano
+es :watches TV brushes his teeth
goes to bed goes to school
does my homework does some reading
y→ i+ es:fly → flies study →studies
不规则变化：have-----has

he, she 都是单数第三人称，动词要加S