As settlers moved to California ___31 the mid-nineteenth century, they became
concerned about the lack of rapid _____32 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.(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(
