This is a key.(变为复数)

This is a key.(变为复数) this is a bus.【变为复数句】 Is this a car?复数Is this a car?(变为复数） Yes,it is.（变为复数） this is a boy is schoolbag 变为复数形式 What is this It is a photo.变为复数形式 is this your key?改句子is this your key?改否定句,肯定句,肯否定回答,把肯定句变为复数句,把复数句变为一般疑问句肯否定回答 This is a pen 变为复数如题 This is a pair of glasses 变为复数 This is a pen变为复数句,怎么变 This is a key.(改为复数形式）（ ）（ ）（ ）（ ）. This is my sister(变为复数句) This is an apple 变为复数句子 Is this your book ? 变为复数句 This is Mary怎么变为复数? What is this?变为复数句___________________________.It is an arm.变为复数句___________________________.This is a foot.变为复数句___________________________.What are these?变为单数句___________________________.These are bags.变为 我父母在第一副相片上怎么说 this is a photo 改为复数句子 school ,key的复数形式 Is this her key?怎么改为复数形式? This is my teacher变成一般疑问句.He is from the U.S.A.变为复数