【高考】You can end up with what astronauts call a carbon-dioxide headache.
【高考】The exercise bike for the American astronauts has no handlebars.
【高考】Bacteria are an annoying problem for astronauts.
【六级】Although, over the years, Barbies had more than 180 different careers, including football coach, sign language teacher, ambassador, president and astronaut, her body shape hasn't changed much.
【高考】One of the nasa's major concerns about astronauts is how they can remain healthy for long in space.
【高考】They come to camp, wanting to know what it is like to be an astronaut or a pilot, and they leave with real-world applications for what they're studying in the classroom.
【高考】Nasa is worried about two things: recovery time once astronauts return home, and, more importantly, how to maintain strength and fitness for the two and a half years or more that it would take to make a round-trip to mars.
【高考】For instance, astronauts lose bone mass.
【高考】The astronauts will suffer from a carbon-dioxide headache when they exercise in one place for a long time.
【高考】If you leave your arms out, they float free in zero gravity, often giving a sleeping astronaut the look of a funny ballet dancer.
【高考】The microorganisms from our bodies grow uncontrollably on surfaces of the international space station, so astronauts spend hours cleaning them up each week.
【高考】Some astronauts feel sick on the station during the first few days because their brains receive contradictory messages.
【四级】It also slows down more as you move faster, which means astronauts (宇航员) someday may survive so long in space that they would return to an Earth of the distant future.