this is my knife改复数句

this is my knife改复数句 That is my knife.改复数句怎么做? This knife is his.怎么改复数形式的句子? This is my shirt.改为复数句怎么改 There is a knife on the desk.改复数句 this is knife in the box（变复数句 My knife is over there.(改为复数句） this is my cousin 改复数句子 He has a knife.改复数句 this is an orange改复数句 This dress is mine改复数句 This is a photo of my family (改为复数形式)为什么不改my family为our families?而This isn't my knife改为复数变为our knives? Whose knife is this?(改成复数) This is a knife 改为复数 Is this your knife 改为复数句子 This is a knife.怎样变复数. Is this her knife变复数 This is a box and that is a knife （改为复数句）