A:was warned; would not take
B:had been warned; would not have take
C:would be warned; had not take
D:would have been warned; had not take
如图所示为仓库中常用的皮带传输装置示意图,它由两台皮带传送这机组成,一台水平传送,A、B两端相距3m,另一台倾斜,其传送带与地面的倾角θ=37°,C、D两端相距4.45m,B、C相距很近.水平部分AB以v0=5m/s的速率顺时针转动.将一袋质量为10kg的大米无初速度放在A端,到达B端后,米袋继续沿倾斜的CD部分运动,不计米袋在BC处的能量损失.已知米袋与传送带间的动摩擦因数均为0.5,求:
下列关于植物的叙述正确的是( )
你知道“苏湖熟,天下足”这句话表明了两宋时哪个地区成为全国最重要的粮仓( )