Is this your? 可以吗

Is this your? 可以吗 is this your pen blue可以这样问吗 Is this your sister?可以这么回答吗?No,she isn't. this is your handbag 这句话中哪个是主语,this 是代词可以做主语吗? this is 可以写成this's 吗? is this your case 语法错误吗? Is this your cousin 中有错吗 Is this your brother? Is this your (空格) Is this your pen? Is this your uncle? Is this your pencil?