They are his friends改为单数形式

They are his friends改为单数形式 Are those his friends?改为单数形式 they are our animal friends改为单数形式 They are my friends.改为单数句 are they your gongd friends 改为单数或复数形式.怎么改? they are English books.(改为单数形式) They are Chinese【改为单数形式】 are they apples?改为单数形式 they are your sons改为单数形式 they are nurses改为单数形式 改为单数形式They are women teacher? They are English cars.(改为单数形式)