单选题 It usually takes much (less) time to fly from one country to (another) than (traveling) (by) train.
A. less B. another C. traveling D. by

【正确答案】 C
【答案解析】[解析] 平行结构错误，应改为to travel。to travel与to fly是两个相比较的平行的结构，故应保持结构一致。