it`s joan`s这里joan的后面为什么要加s

it`s joan`s这里joan的后面为什么要加s Joan Joan Liu Ying gives me more help than____.(a) Joan is (b) Joan gives (c)Joan's help(d)Joan does What's her name?Her name's Joan White .She is White Joan.哪个是对的 ?uncle is an engineer为什么是Tom and joan's而不是tom's and joan's tom's and joan tom and joan 根据句意填空.Ann and Joan are( 1 ) .They look( 2 ) each other very much.People often ( 3 ) that Ann is Joan or Joan is Ann, ( 4 ) it's to tell the difference.上面一句的t's和to之间还有一个空，第二句以下为准。People how many children does Mr Green have?3.Mary,Joan and Jack.Mary is____sister.A Joan and Jack's B Joan's and Jack's color,dress,is,Joan's,what 连词成句 Is Mary Sally and joan's mother?啥意思啊 _______will go together with us for the picnicA.How many friends of JOan's.B.How many JOan's friends joan’s telephone is red （对划线部分提问,划线部分为red） （ ）（ ）（ ）joan’s telephone? The woman (in blue) is Joan's mother.对括号部分提问.（ ）woman（ ）Joan's mother?一空一词 it's bound to be 如题前三个好像都不太对啊……上下文是：joan:the indian restaurant is supposed to be excellent...the RAJDOOT.peter:how do you spell that?joan:R A J D O O T.peter:but it's bound to be packed.joan:well,let's put that d joan the 选择题--What colour are Tom's shorts?--What colour are Tom's shorts?--_____A.It's green B.Yes,it is C.It is Joan's D.They're red 英语智力题,今天要用~Joan's husband is the grandpa of my son.I am Joan's_____.A.grandson B.son C.father D.grandpa哇呜T_T Joan's mother seldoom_______shopping at the weekend. A.go B.goes C.going