this is a pencil box 的复数形式

It is a red pencil box.变成复数形式. This is a box.改为复数形式 This is a pencil box.对a pencil box 提问 This is a pencil box.(对” a pencil box”提问 ) pencil-box的复数形式是什么? What is this? It is a box.复数形式 1.A new knife is in the pencil box.(用some将句子改为复数形式) 句型转换.1.This is a pencil- box.（改为复数句）_______ ______ ______pen where is my pencil-box?(改为复数形式） Where is my pencil-box （改为复数形式） This is his pencil-box.改为复数句子怎么改? is this your pencil-box?的答语