3类仿制药:a piece of paper money

a piece of paper money a sheet of paper和a piece of paper的区别？ a red piece of paper 为什么red要放前面 This is a piece of paper,Youcan get some news from it. What is it A PIECE OF CAKE a piece of chalk there was also a piece of paper on the bank where he had just put his clothes there was also a piece of paper on the bank where he had just put his clothes A piece of cake ! look! Quiz :a piece of cake !