----How long does it take us to go to your hometown from here?--It takes us hour or mor

问题补充：

----How long does it take us to go to your hometown from here?

----It takes us hour or more to go to my hometown bytrain.

A. an; a

B. a ; an

C. an; /

D. a; /

答案：

A. an; a

B. a ; an

(答案→)C. an; /

D. a; /

解析：冠词的考察 hour [au?]第一个字母h不发音，所以一小时应用an hour; by 介词，当交通工具前无修饰词时，用介词by且名词前不用冠词。