This is your sister.改为复数形式急

Is this your sister是什么意思 Is this your sister?与Is she your sister?区别 IS this your sister?(改为复数句) Is this your sister?的答语是? is this your sister的答语是 Is this your sister?否定回答RT is this your sister 的肯定回答是?is this your sister 的肯定回答是? Is this your sister 答语为什么要用it is. Is this ( ) your sister,Linda?Yes,She is. Is this your sister 与Is she your sister?的区别 This is your sister.改为复数形式急 IS this your sister?(改为复数句） Is this tall girl your sister?该肯定句 is this your brother?的回答与is this girl your sister?的回答的区别 She is your sister Is that ( ) your sister are this your sister?改错 Is this your sister?英语语法Is this your sister?No,it isn't.Is that your brother?Yes,it is.为什么这里的“your sister”、“your brother”在回答时要用“it”代替?可以用“she”或“he”代替吗?