【单选题】听力原文: In the Middle Ages two was the official number of meals because of the clergymen's insistence on fasting. But this official pattern was frequently changed for some practical reasons. For example...
C.
By the end of last century
【单选题】根据铁路边界噪声限值及测量方法中规定,铁路边界夜间噪声等效声级LAeq限值为( )dB。
【单选题】铣削是( )旋转作主运动,工件或铣刀作进给运动的切削加工方法。
【单选题】铣削加工时,A同学说主运动是工件的进给运动,B同学说,主运动是铣刀的进给运动,C同学说你们都不对,应该是铣刀的旋转运动才是主运动,你认为( )是正确的。
【单选题】汽车上交流发电机配装了调节器后,具有( )
【单选题】铁路边界噪声夜间噪声限值为( ) dB(A)。
【判断题】铣削加工是工件旋转作主运动,刀具作进给运动的切削加工方法。