第二节：语法填空（共10小题，每小题1.5分，满分15分）
阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空，并将答案填写在答题卷标号为31-40的相应位置上。
As settlers moved to California ___31     the mid-nineteenth century, they became
concerned about the lack of rapid _____32    (communicate) with the eastern United States. Because of the dangers and hardships of ___33   (cross) the West, mail often did not arrive. Therefore the most important mails _____34    (send)  via Panama, ____35    took a month or more. In 1860 a stagecoach company decided to meet the problem by beginning the Pony Express. The company hired __36   bravest riders and bought the fastest horses __37   (use) as relay(替换) teams between Missouri and California, and the company promised __38     mails would be sent in ten days. The company established two hundred stations along the route at which riders could rest and change horses. In less than two years, __39  , telegraph lines were completed and the Pony Express was ___40     longer needed.