this is a pencil改为复数句

this is a pencil改为复数句 This is a pencil case.(改为复数句子） that is a pencil.改为复数句 Exuse me!Is this your pencil case?改为复数形式 This is my pencil case改为复数形式 This is his pencil-box.改为复数句子怎么改? this is a pencil 改为一般疑问句 IS this his book?改为复数句 This is my pencil.改为同义句 This is my pencil.（改为复数句） It's his backpack.（改为复数句） Is's a pencil-box.改为复数句 将下列单数句改为复数句 Is this your pencil?Is that your cousin?Where is your key?Is it on the chair?This is a dog. This is a pencil sharpener.(改为一般疑问句) This is a pencil box 改为一般疑问句 this is a short pencil （改为同义句） This is a short pencil.改为同义句 that is his pencil改为复数句 This is a book 改为复数句 This is a pear.改为复数句