麻花钻在主切削刃上的前角是变化的,靠外缘处前角最大,从外缘到钻心由大逐渐变小。接近横刃处的前角γ°=-30°。( )
参考答案:对
The next stop is Beihai Stop. If you want to go to Beihai Park, please prepare to _____.[ ]
A. wake up
B. take off
C. get off
D. sit down
旅游界有这样的口碑:“秦唐文化看西安,明清文化看北京。那两汉文化看哪里?