如图所示，弹簧振子以O为平衡位置，在B、C间振动，则(　　)．

A．从B→O→C→O→B为一次全振动

B．从O→B→O→C→B为一次全振动

C．从C→O→B→O→C为一次全振动

D．OB的大小不一定等于OC

He looked around and caught a man _____ his hand into the pocket of a passenger.

A．put

B．to be putting

C．to put

D．putting