打击与保护，两者是紧密联系、相互依存、相互渗透，但保护以打击为前提。 ( )
参考答案：错
实验室在放干燥箱、马弗炉的地面上垫上绝缘橡胶是为了防止操作人员在工作过程中触电。
What impressed the visitors deeply was ______ the workers made with their hands.
A．what
B．that
C．how
D．which
