消毒染有霍乱弧菌食具的最佳消毒措施是
A．紫外线B．煮沸C．2%漂白粉D．3%的来苏儿E．3%的石炭酸
参考答案：B
分解因式：2a2-4a+2=（ ）。
_______ is known to us all that the 2010 World Expo took place in Shanghai.
A．It
B．As
C．Which
D．What
