The man we followed suddenly stopped and looked as if          whether he was going in the right direction.

A．seeing

B．having seen　

C．to see

D．to have seen

下列事例中，属于防止惯性的是 [ ]

A．跳远运动员在起跳前要助跑

B．为了安全行驶，汽车不能超载

C．拍打衣服，可以把衣服上的尘土拍掉

D．停止蹬自行车后，车仍能前进一段距离