Those are old yellow shirts改为单数句

Those are old yellow shirts改为单数句 请问 those shirts are blue（改为单数句子） Those are old boxes. (改为单数) Those are old libraries.改成单数句 These are yellow purses.(改为单数句) Those are my friends 改为单数句 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 Are those your cups?改为单数句 Those are erasers.(改为单数句）