The silk road, Marco entered China, was important for the exchange of goods and ideas.
A. which
B. along which
C. after which
D. where
网友回答
A. which
(答案→)B. along which
C. after which
D. where
解析：考查定语从句。先行词是The silk road，代入定从 Marco entered China，应是Marco entered China along the silk road.所以选B。