this is my book.写出下列句子的复数形式

this is my book.- These are my/our books.
Is that his uncle - Are those his/their uncles
Is she your friend?- Are they your friends
yes,it is.- Yes,they are.
this is my pencil case.- These are my/our pencil cases.
不明白的再问哟,请及时采纳,多谢!
再问： O(∩_∩)O谢谢 还有道题 连词成句(注意句后的标点符号) 1.sister,this,your,is_________________? 2.is,not,your eraser,that_______________. 3.friends,his,are,those_______________? 4.are,brothers,my,these_____________. 谢谢
再答： 1. Is this your sister ? 2. That is not your eraser. 3. Are those his friends ? 4. These are my brothers.