It is white,It is like a flower,blooms in winter,flies in the sky,falls to the ground.what is it?

---What is this_________?It is white ruler. it is clean when it is black.it is dirty when itis white.what is it Is it green?Is it white?(改为选择疑问句) white ,black ,it,and,is,连成一句话 It's ( ) pet.( ) is white.填空. 猜谜语：It is clean when it is black.It is dirty when it is white.What's 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? Look the whole world is white .it is (s )heavily what is white when it is dirty 猜猜what是什么 It is( )hard.The ground is so white now what color is it? it is ______.black and white and/white/a black/a black and white 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 biack when it is ciean and white when it is dirty?(翻译意思）