加工硬化
参考答案：
工件已加工表面层因切削变形而发生硬度、强度提高，塑性韧性下降的现象。
There is no doubt that holding such ____ National Day parade will significantly enhance (提高) ____ national
pride and self-confidence of Chinese People. [ ]
A. a; the
B. a; a
C. the; the
D. the; a
交流耐压试验的试验时间一般不长，可采用冲击合闸的方法给被试物加压或减压。（）
