【正确答案】 C

【答案解析】[听力原文]
Located at the NASA research center in Iowa, there is a 5000 gallon container of water. And inside the tank is an underwater treadwheel designed by Davan Newman, an aerospace engineer. For four years, Newman observed divers as they simulated walking on the moon and on Mars on her underwater moving belt. She wanted to discover how the gravity of the moon and of Mars would affect human movement. To do this, Newman attached weights to the divers and then lowered them into the tank and onto the treadwheel. These weights were carefully adjusted so that the divers could experience underwater the gravity of the moon and of Mars as they walked on the treadwheel. Newman concluded that walking on Mars will probably be easier than walking on the moon. The moon has less gravity than Mars does. So at lunar gravity the divers struggled to keep their balance and walked awkwardly. But at Martian gravity, the divers had greater traction and stability and could easily adjust to a pace of 1.5 miles per hour. As Newman gradually increased the speed of the treadwheel, the divers took longer, graceful strides until they comfortably settled into an even quicker pace. Newman also noted that at Martian gravity, the divers needed less oxygen. The data Newman collected will help in the future design of Martian spacesuits. Compare to lunar spacesuits, Martian spacesuits will require smaller air tanks. And to allow for freer movement, the elbow and knee areas of the spacesuits will also be altered.

What did Newman change so that the divers could experience different gravity levels?

短文开头提到了一个水下踏车，纽曼用它来观察模仿在月球和火星行走的潜水员。纽曼想发现月球和火星的引力如何影响人类行动。当潜水员在水下踏车上行走的时候，她通过调整系在潜水员身上的重量来使其感受月球和火星的引力，因此答案为C。

【正确答案】 A

【答案解析】[听力原文]
Why will Martian spacesuits be designed differently from lunar spacesuits?

纽曼通过实验得出结论：在火星上行走可能比在月球上行走容易，因此答案为A。

【正确答案】 D

【答案解析】[听力原文]
What happened to the divers at Martian gravity when the speed of the treadwheel was increased?

当纽曼逐渐提高踏车的速度时，潜水员步伐更大，姿势更优美，直至他们轻易地适应更快的行走速率，因此答案为D。

【正确答案】 C

【答案解析】[听力原文]
What is one way that the design of Martian spacesuits will differ from lunar spacesuits?

短文最后提到火星服的特点：与月球服相比，火星服只需要体积更小的氧气罐，而且为了更自由的活动，太空服的肘部和膝部也将改变，这意味着火星服会更具灵活性，适合活动，因此答案为C。