Are those your friends?(改为单数句)

Are those your friends?(改为单数句) Those are my friends 改为单数句 Are those your cups?改为单数句 This is Gina‘s brother（改为复数句） Are those your friends?（改为单数句） Are those his friends?改为单数形式 Those are my friends怎样改为单数句?什么是单数句? This is an orange(改为复数句） Those are my friends.改为单数句 Are thes those are orange towels改为单数句 Those are oranges（改为单数句） those are my brothers.改为单数句 Are those pens改为单数句 Those are erasers.(改为单数句）