What is biack 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 biack when it is ciean and white when it is dirty?(翻译意思） 猜谜语：What a room has no walls,no windows,and no floors?it还有：What is biack when it is clean white when it is dirty?it不许乱回答,不然连一根毛也不给你 It is biack and Which is biack when you buy it,red when you use it,and gray when you throw it away Which is biack when you buy it,red when you use it,and gray when you throw it away 英语谜语：when I am white,I am dirty.when I am biack,I am ciean.what am 英语谜语答案1.letter is an insect?2.What is biack when it is clean and white when it is dirty?3.What will you get if you cut the head of a bear?4.why is a river rich? biack BIACK, biack My family name is biack 汉语意思 英语连词成句biack it jacket a is biack it jacket a is What's in it?Look,this is a pen.It's biack.This is a pencil.It's red.(翻译这句话） this bag is three dollaes就划线部分提问 画线为three dollars.how much are these biack shoes?回答__four dollaes l want green 变成what 问句 This is( )good pen ( )color of theWis biack what is white when it is dirty 猜猜what是什么 what about you?when is your birthday?