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。