_____ around the Water Cube, we were then taken to see the Bird's Nest for the 2008 Olympic Games.[ ]

A. Having shown

B. To be shown

C. Having been shown

D. To show

某条铁路线上，包括起点和终点在内原来共有7个车站，现在新增了3个车站，铁路上两站之间往返的车票不一样，那么，需要增加多少种不同的车票( )

A．35
B．48
C．90
D．210