1,Isthisyoursister?No,itisn’t.
Issheyoursister?No,sheisn’t.
2,earemyfriends.
earemybrothers.
3,ismyfamilyphoto.
photoofyourfamily=yourfamilyphoto
可数名词单数变复数:一般情况下加s,book-books,以s,x,sh,ch结尾的'加es
watch-watches以辅音字母加y结尾的,把y改为i再加esboy-boys,family-families以o结尾的有生命的加es,无生命的加s,tomato-tomatoes,photo-photos