问题：
【名词解释】助力运动
答案：
助力运动是一种医疗体操。进行时病残者凭借他人或健肢及器械的帮助，使患肢活动并完成一定的动作。要求患肢亦主动用力，外力帮助主要加在患肢活动范围的起始和结束部分。随着患肢肌肉力量的恢复和加强，逐渐减少辅助力。适用于创伤后无力肌肉或不全麻痹肌肉的功能锻炼，可增强肌力，使动作协调。 [1] [听力原文]36-46 Let’s proceed to the main exhibit hall and look at some of the actual vehicles that played a (36)prominent role in speeding up mail(37) delivery. Consider how long it used to take to send a letter across a(38) relatively short distance. Back in the 1600s, it took two weeks on horseback to get a letter from Boston to New York. a distance of about 260 miles. Crossing a river was also a (39) challenge. Ferry service was so (40) irregular that a carrier would sometimes wait hours just to catch a ferry. For journeys inland there was always a stagecoach but the ride was by no means(41)comfortable because it had to be shared with other passengers The post office was pretty (42) ingenious about some ways. In the 19th century, in the southwestern (43) desert, for instance, camels were brought in to help to get trail through. In Alaska, reindeer were used. (44) This practice was discontinued because of the disagreeable temper of these animals. We’ll stop here a minute so that you can enter this replica of a railway mail Car. (45)It was during the age of the iron horse that delivery really started to pick up. In fact, the United States transported most bulk of mail by train for nearly 100 years. The first airmail service didn’t start until 1918. Please take a few moments to look around. I hope you’ll enjoy your tour. And as you continue on your own, may I suggest you visit our impressive philatelic (集邮的)collection (46) Not only can you look at some of the more unusual stamps issued but there’s an interesting exhibit on how stamps are made.