This is a book和This is a bag 和This is a pen和This is a pencil和This is a ruler 的复数咋写.还有This is a pencil-box 复数怎么写 快点我来不及了

This is a book Is this a book? Yes,this is. This is a book答语 This is s book.(a book提问) This is a new book的疑问句和回答 This is a book of mine.和This is a book of me.哪句话对?为什么? This is a book 改为复数句 This is a interesting book.找错误! this is a book改为复数形式 This a book is good 怎么改错 Is this a book?的复数句 改错题：This is a my book. This is a book变成一般疑问句 this is a nice book的感叹句? This is a nice book,____it?填空 改错This is a expensive book This is a book.(It's,Its) this is a book on ________(electronic)