問題詳情

IV. Reading Comprehension: Choose the best answer to each question.In July 1969, the world watched as two men set foot on the Moon. For the first time, humanity had ventured out of the planet and touchedthe possibility of worlds beyond. But our space travel ambitions seem to have stalled since the 1970s and 1980s. In over 30 years, we've venturedvirtually no further than the original pioneers. And as more astronauts have spent more time aboard the various space stations, they have reportedworrying health problems.As recent tragic events have shown, the most dangerous part of any space journey is taking off. Trying to reach the speeds needed to escapeEarth's gravity is fraught with peril. But even once they reach space, astronauts are not out of danger. Instead, they are exposed to a new set ofrisks which we are only just beginning to understand.Astronaut Chris Hadfield spent months living in space aboard the International Space Station. According to Hadfield, zero gravity changedhis body and how he lived with the constant threat of high-speed micrometeorites.We were made to live on Earth, not in the extreme conditions we find in space. So when astronauts like Chris Hadfield leave our planet,they have to take their environment with them. That’s why they wear specially-designed spacesuits. But spacesuits do much more than just keepEarth's atmosphere around astronauts. Over the years, spacesuit design has evolved to protect humans from the harshness of space.In Earth's orbit, astronauts might experience temperatures as low as -129°C (-200°F) and as high as 121°C (250°F). Spacesuits have beencleverly designed to protect us from these extreme conditions. They also provide air pressure to prevent our bodily fluids from boiling in the hardvacuum of space. But astronauts can only travel so far in the spacesuits that exist today. Even our best suits are limited to a ‘low-Earth orbit’. Topush farther into the Solar System, we will need a new suit – one that will shield us from the lethal hazards of deep space. But even then, are westurdy enough to survive a long mission?A spacesuit may protect us externally, but space can have devastating effects on the internal workings of the human body. On Earth, wehave evolved to work in harness with gravity. Our muscles and bones have developed to expect this force and it is needed to keep them strongand healthy. In space, astronauts float weightlessly. This looks like a lot of fun, but prolonged exposure to a microgravity environment can haveinsidious effects on the human body.Space travel plays havoc with our blood circulation. Human cardiovascular systems are designed to pump blood steadily around the bodyagainst the force of gravity, which normally pulls blood towards our feet. But in the microgravity of space, blood moves up to the chest and head,giving astronauts puffy faces and raised blood pressure.Muscles are also threatened by space travel. Without the need to work against gravity, muscles can start to waste, which increases the riskof tendonitis and fat accumulation. The lack of gravity even makes astronauts stand up to two inches taller, as back vertebrae separate without thecompression of gravity, leading to painful back-aches.Over the long term, astronauts suffer the devastating consequences of bone loss. Microgravity causes the body to lose calcium andphosphorus, leading to a gradual weakening of bone and an increased risk of osteoporosis. Bone loss can be as high as 1.5% of its mass permonth, which is roughly 10% over a six-month stay in space, with the recovery after returning to Earth taking at least three to four years. In anattempt to combat this, astronauts living on the International Space Station must carry out 2.5 hours of exercise a day, six times a week.
41. Osteoporosis refers to the ____________.
(A) bone loss
(B) slow growth
(C) weight problem
(D) blood pressure

參考答案

答案：A
難度：適中0.5
統計：A(0),B(0),C(0),D(0),E(0)

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