VOA慢速英语:Mailing a Letter to California in the Old West

1.There used to be a time when the quickest way to travel across the western United States was in a stagecoach.

used to过去一向,过去时常;过去曾(而现在不再)做

例句：The Greeks used to worship several gods.
      过去,希腊人崇奉好几种神。

2.In return, he had to promise that the mail would travel from Saint Louis, Missouri, to San Francisco, California, in twenty-five days or less.

in return反过来

3. It went out of business because of the Civil War, which began that year.

go out of business停业, 歇业

例句：Some of old newspapers had to go out of business for low sales.
      有些老的报社由于销量低而倒闭了。

      This shop has gone out of business for two months.
      这家商店已经停业两个月了。

4.on account of the number of pine trees that grow in the gorge of the mountain in which it is situated.

on account of由于

例句：Bill cannot come to the meeting on account of illness.
      比尔因病不能到会。