Is this a pen?（变复数句）

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 pen变复数 this is a pen.改为复数句 that is his pen变复数句 英语~①This pen is in the pencil-box（变复数）①This pen is in the pencil-box（变复数）②Those red watches are Jim's（变单数）③She is a good girl（变感叹句）④Her friend goes to shanghai every month（变否定句,一般 This is a marker.（变复数） This is a pen.(改为复数形式) This is a horse.变该句为复数形式 this is a box.变复数句___________? this is a marker怎么变复数句 she is a teacher.变复数 it is a pen.变复数 this is myshe is a teacher.变复数 it is a pen.变复数this is my friend.变复数的一般疑问句,并做肯定及否定回答 英语 改复数句This is a pen.Is this your backpack?It's a black bag This is a[backpack]变否定句、对画框部分提问、变复数句RT This is an eraser That is aThis is an eraserThat is a plate变复数句 What's this?It's a pen.(改为复数句) This is a red tomato .(变复数）