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There’s a planet next door that could explain the origins of life in the universe. It was probably once covered in oceans. It may have been able to support life for billions of years. No surprise, astronomers are desperate to land spacecraft there. The planet is not Mars. It’s Earth’s twin, Venus. Despite its appeal, the second planet from the sun is one of the hardest places in the solar system to get to know. That’s partly because modern Venus is famously hellish. No spacecraft have landed on the surface of Venus since 1985. A few spacecraft have visited Earth’s neighbor in the past decade. For example, the European Space Agency’s Venus Express visited Venus from 2006 to 2014. However, no NASA craft has visited Earth’s twin since 1994. That’s when the Magellan craft crashed into the atmosphere of Venus and burned up. The planet’s atmosphere is 96.5 percent carbon dioxide. That blocks scientists’ view of the surface in almost all wavelengths of light. To really understand the surface, scientists want to land a craft there. It would have to deal with the cloudy atmosphere while looking for a safe place to touch down. The best map of the planet’s surface is based on radar data from Magellan a quarter century ago. Its resolution ( 分辨率 ) is too low to show rocks or hills that might destroy a lander. James Garvin is a member of a team in NASA that is testing a computer-vision technique. Called Structure from Motion, it could help a lander map its own touch-down site. It would do this during its falling process. The system quickly analyzes many images of the ground taken from different angles. This allows it to create a 3-D picture of the surface. Garvin’s group tried it out in Maryland. It was able to identify rocks less than 19.5 inches across. That’s about the size of a pumpkin. Any lander that successfully reaches the surface of Venus faces another challenge. The first landers there were Soviet spacecraft. They landed in the 1970s and 1980s. Each lasted only an hour or two. That’s not surprising. The planet’s surface is about 460°C. But a team at NASA’s Glenn Research Center in Cleveland, Ohio is hoping to do far better. It aims to design a lander that would last months. Past landers have used their bulk ( 体积 ) to absorb heat, which can’t last long. Or they have dealt with extreme temperatures with a special cooling system. This team proposes something new. They plan to use a brand new material — silicon carbide. This material should withstand the heat and enable the craft to do a reasonable amount of work.
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【多选题】下列哪些情形为劣药()
A.
药品成份的含量不符合国家药品标准;
B.
被污染的药品
C.
未标明或者更改有效期的药品
D.
未注明或者更改产品批号的药品
E.
药品所含成份与国家药品标准规定的成份不符的
F.
超过有效期的药品
G.
擅自添加防腐剂、辅料的药品
H.
其他不符合药品标准的药品
【多选题】下列哪些情形的药品为劣药
A.
超过有效期的
B.
变质的
C.
没有有效期的
D.
没有生产批号的
E.
改变成分的
【多选题】下列哪些情形的药品为劣药
A.
超过有效期的
B.
变质的
C.
没有有效期的
D.
没有生产批号的
E.
没有批准文号的
【多选题】提出的“三步走”发展战略是指()。
A.
第一步是从1981年到1990年实现国民生产总值比1980年翻一番,解决人民的温饱问题
B.
第二步是从1991年到20世纪末,使国民生产总值再翻一番,达到小康水平
C.
第三步是到21世纪中叶,国民生产总值再翻一番,达到中等发达国家水平,基本实现现代化
D.
第三步是到21世纪中叶,国民生产总值再翻两番,达到中等发达国家水平,基本实现现代化
【简答题】催化裂化催化剂经历了________、________、____催化剂。
【多选题】下列哪些情形为劣药( )
A.
药品成分的含量不符合国家药品标准
B.
被污染的药品
C.
超过有效期的药品
D.
擅自添加防腐剂、辅料的药品
E.
未注明或者更改产品批号的药品
【多选题】下列哪些情形为劣兽药( )。
A.
成分含量不符合兽药国家标准或者不标明有效成分的
B.
不标明或者更改有效期或者超过有效期的
C.
不标明或者更改产品批号的
D.
其他不符合兽药国家标准,但不属于假兽药的
【单选题】现代家具大多采用人造板作为基材,为了充分利用胶合板、中密度纤维板以及表面质量较差的刨花板,通常需要对它们进行( )。
A.
贴面处理
B.
油漆
C.
绘画
D.
雕刻
【单选题】以下不属于高效液相色谱仪的组成的是( )
A.
高压输液系统
B.
进样系统
C.
分离系统
D.
温度控制系统
【单选题】以下医家认为《伤寒论》原文不需要进行重新编排的医家是( )?
A.
方有执
B.
黄元御
C.
陈修园
D.
喻嘉言
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