问题补充：
The public transportation is very convenient in that big city, so there be any difficulty in traveling around.
A. mustn
B. wouldn
C. shouldn
D. needn
答案：
A. mustn
B. wouldn
(答案→)C. shouldn
D. needn
解析：选C考查情态动词。句意：那个大城市的公共交通很便利，所以旅行应该不会有什么困难。shouldn 表示推测，意为“不应该”，把握较大。mustn 表示禁止。
