问题补充：
Walk the bridge and then turn left the right at the first turning .
A. along, at
B. in, to
C. across, on
D. through , in
答案：
A. along, at
B. in, to
(答案→)C. across, on
D. through , in
解析：along沿着;at表示在空间的一点;to做介词表示到哪儿;across穿过,强调从表面横穿;through穿过,强调从内部通过.on表示在那个表面.结合句意:走过这座桥,然后在第一个路口向左转.故选C.
