As settlers moved to California     1     the mid-nineteenth century, they became concerned about the lack of rapid     2     (communicate) with the eastern United States. Because of the dangers and hardships of     3     (cross) the West, mail often did not arrive. Therefore the most important mails     4     (send) via Panama,     5     took a month or more. In 1860 a stagecoach company decided to meet the problem by beginning the Pony Express. The company hired     6    bravest riders and bought the fastest horses     7     (use) as relay(替换) teams between Missouri and California, and the company promised     8    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,     9     , telegraph lines were completed and the Pony Express was     10     longer needed.