EN分布图目的:让管理人员更容易掌握客户订货品种数的分布情形,以决定使用的拣货方式,并可由分布图判断物品拣货时间与拣货人力需求,依次作为拣货作业的生产力指针。
参考答案:对
David has bought a large house with a swimming pool. It _____ be very expensive. [ ]
A. must
B. can
C. mustn't
D. can't
如图所示,在倾角为θ的光滑斜面A点处,以初速度v0与斜面成α角斜抛出一小球.小球下落时将与斜面做弹性碰撞.若小球返跳回出发点A,则α、θ满足的条件是( )
A.cotαcotθ=k
B.cotαtanθ=k
C.sinαcosθ=k
D.cosαsinθ=k