the most wonderful piece of machinery on show was Nasmyth's steam hammer.
问题描述：
the most wonderful piece of machinery on show was Nasmyth's steam hammer.
请问piece,启什么作用,如何去理解
答
machinery是机械、机器的总称,如果要说一个机器、一台机器,要用量词,a piece of machinery一台机器设备
就象纸paper是不可数名词,说一张纸要说：a piece of paper 或 a sheet of paper,就变成可数名词了