The lady walked around the shops, _____ an eye out for bargains.[ ]

A. keep

B. kept

C. keeping

D. to keep

如图所示，物体静止在水面上，画出它所受力的示意图；请在图所示的杠杆中标出其工作时阻力臂和作用在A点的最小动力的方向及力臂．