A.How long does it take to go to the library by bus?

B.How long does it take to go to the hospital by bike?

C.How long does it take to go to the library on foot?

【答案】C

【解析】

A意为坐公共汽车去图书馆要多久，B意为骑自行车去医院要多长时间，C意为步行去图书馆要多久，结合题干可知，AB不正确，故选C。