That book is his?改为复数形式

Whose book is that?改为复数形式 is that his key (改为复数形式) that is his sister改为复数形式 That is his book.怎么改为复数句 This book is in that box.（改为复数形式） There is a book.改为复数形式 this is a book改为复数形式 Is that her English book?复数形式 This is his sister and that is his son.怎么改为复数形式 That is my sister改为复数形式 This is his cousin改为复数形式 I'm Mike Sm This is my brother.改为一般疑问句 that is his photo.改为复数形式 改为复数形式 Is that an English book?What"s this in English?It is