Is this Lucy's schoolbag? No,it's not hers."hers"这一个用的对不对?

This is Lily's and lucy's mother.纠错 this is lily`s and lucy`s room 改错 This bedroom is Lucy's and Lily's 改错 The desk is Lucy and Lily's.{Lucy and Lily's画线} —— is this? --whose watch is this ?---【 】,回答为什么不能是this is lucy‘s 而是it is lucy’s,请解释,谢谢 This T-shirt is Lucy’s对Lucy’s划线提问 Tom,this is M______ Black,Lucy's mother.如题. This is Kate's and Lucy' room这句话对吗 This ruler is Lucy’s .Please give it to（）. This room is ___ .A.Lucy and Lily B.Lucy's and Lily C.Lucy's and Lily's D.Lucy and Lily's 语法说明 This is ( ) father,Mr.Smith.A.Lucy and Lily B,Lucy's and Lily's C.Lucy and Lily's D.Lucy's and Lily 是Look at this photo of lucy's还是Look at this photo of lucy?原题是—Look at this photo of ___!Is there a smile onher face?—Yes,and this photo is the best one of ___.A.Lucy's Lucy'sB.Lucy LucyC.Lucy's LucyD.Lucy Lucy's第二空也是同样 --Who's this?--( ) is Lucy.下面四项选什么?为什么?This/It/That/She 英语选择题This bedroom isn't ( )and ( )is on the second floor.A.Lucy and Lily's,theirsB.Lucy's and Lily's,theirsC.Lucy and Lily's,theirD.Lucy's and Lily's,their 英语选择题：Who's that? ( ) is Lucy. A This B It C That D She's Is this Lucy's schoolbag? No,it's not hers.hers这一个用的对不对? this is lucy.her mother is my aunt.she's my c___. This bike is Lilys,This bike isLucys.They are Lily and Lucys写得对吗详细说明