it is clean when it is black.it is dirty when itis white.what is it

it is clean when it is black.it is dirty when itis white.what is it It is clean when it is black.It is clean when it is black.It is dirty when it is white.what's it? 猜谜语：It is clean when it is black.It is dirty when it is white.What's it 智力测试What is black when it is clean and white when it is dirty? What is clean when it is black and dirty when it is white? What is black when it is clean white when it is dirty? what is black when it is clean and white when it is dirty是----- What is black when it is clean and white when it is dirty? What is biack when it is clean and white when it is dirty? What is clean when it is blanck and dirty when it is white? That is black when it is clean and white when it is dirty What、is、black、when、it、is、clean、and、when、it、is、dirty·谜底是什么? It is very()(clean). 【what is clean when it black ,and white when it is dirty. 英语：读一读,想一想,猜一猜What is black when it is clean and white when it is dirty?It is a ( ). What is black when it is clean and white when it is dirty?求求啦!我弟的寒假作业. what is black when it is clean and white when it is dirty?用英语怎么回答 It is nice and clean