题干
-- Did you see a man in black pass by just now ?
--No , sir. I _____a newspaper .
A：read
B：was reading
C：would read
D：am reading
答案(点此获取答案解析）
B
A：read
B：was reading
C：would read
D：am reading
，若升降机以加速度g向下做匀加速运动时，以下关于物体受力的说法中正确的是( )