As settlers moved to California in the mid-nineteenth century, they became concerning about the S1.______ lack of rapid communication with the eastern United States. Because the many dangers and hardships of S2.______ crossing the West, mails often did not arrive. The S3.______ most important mail was therefore sent via Panama, took a month or more. S4.______ In 1860 a stagecoach company decided to meet S5.______ a problem by beginning the Pony Express. The company hired the bravest riders bought the fastest horses S6.______ to be used as relay teams between Missouri with California, S7.______ and the company promised that mail would be delivering in ten days. The company established two S8.______ hundred stations along the route on which riders could S9.______ rest and change horse. In fewer than two years, however, S10.______ telegraph lines to San Francisco were completed and the Pony Express was no longer needed. 【S1】
A.______ lack B.______ crossing C.______ most D.______ E.______ a F.______ to G.______ and H.______ hundred I.______ rest J.______ telegraph K. 【S1】