题目

What were you doing when the World Trade Center in New York _________ terrorists.        A. destroyed by                          B. destroyed to              C. was destroyed by                    D. was destroyed to      答案：C把铁粉放入硝酸银、硝酸铜和硝酸锌的混合溶液中，充分反应后过滤，所得固体中一定没有的是（ ）A．锌B．铁C．铜D．银