题型:判断题 While she ______ the newspaper, her sister ______ asleep. [ ]A. read; fell B. was reading; was falling C. read; was falling D. was reading; fell 查看答案
题型:判断题 如图所示,轻质光滑滑轮两侧用细绳连着两个物体A与B,物体B放在水平地面上,A、B均静止.已知A和B的质量分别为mA、mB,绳与水平方向的夹角为θ,下述正确的是( )A.物体B对地面的压力可能为0B.物体B受到的摩擦力为mAgcosθC.地面对B的作用力方向竖直向上D.地面对B的作用力方向斜向左上方 查看答案