英语 改复数句This is a pen.Is this your backpack?It's a black bag

英语 改复数句This is a pen.Is this your backpack?It's a black bag this is a pen.改为复数句 Is this a pen?（变复数句） This is a pen变为复数句,怎么变 this.is pen变复数句 This is an apple.that is a pen.改复数形式 Is this a plane?yes,it is 改复数句 This is a pen.(改为复数形式) is this a boy or a girl改复数句 英语改句子变否定句一般疑问句肯定回答否定回答复数句：this is her futher.this is my good friend.he is abrave boy?it is a yellow quilt?that is your pencil case.this is his book.iam fine.her pen is yellowandwhite.my idcard is bi this is an orange改复数句 This dress is mine改复数句 this is my knife改复数句 This is pen变复数 英语改否定句 Is this a ruler 如何改 What's this?It's a pen.(改为复数句) This is a garden改复数 this is a ruler.改复数