问题补充：
As soon as they arrived in the big city ,they found it difficult to find somewhere cheap
A. to live
B. to live in
C. to live on
D. living
答案：
(答案→)A. to live
B. to live in
C. to live on
D. living
解析：句意：他们一到这个大城市，就发现找到便宜的地方住很难。to do 做后置定语，修饰前面的somewhere cheap，somewhere是副词，故不用介词，故选A.
