（2021·浙江）阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。
NASA will use the International Space Station as a stepping stone for the journey ahead. They will prepare astronauts for the human exploration. Explorers may visit near-Earth planets, 81． we may get answers to the questions humans have always asked. Visiting an asteroid (小行星) will prepare for the first humans to step on Mars.
Robotic exploration continues to deliver answers about our Universe by visiting far-off destinations. When 82． (combine) human and robotic exploration methods, we will use technology to increase our ability to observe and uncover new knowledge. Mars has always been 83． source of inspiration for explorers. Robotic missions have found evidence of water, 84． whether life exists beyond Earth still remains a mystery. So far, the evidence that Mars has characteristics similar to Earth’s 85． (show) by robotic missions. Humans can build upon this knowledge and look for signs of life on Mars, resulting in research and methods that could be applied here on Earth.
A mission to our nearest neighbor provides the best opportunity to show that humans can live beyond the Earth. The technology and space systems 86． (require) to transport explorers will encourage creative ways to address challenges. The challenge of traveling to Mars and learning how to live there will encourage 87． (nation) to work together to achieve such an ambitious undertaking. The International Space Station has shown that opportunities for cooperation will highlight our common interests and provide a 88． (globe) sense of community.
81．where
82．combining
83．a
84．but
85．has been shown
86．required
87．nations
88．global
【分析】
这是一篇说明文。美国宇航局将把国际空间站作为未来旅程的踏脚石，文章对此进行了介绍。
81．
考查定语从句。句意：探险家可能会造访近地行星，在那里我们可以得到人类一直问的问题的答案。在非限制性定语从句中不缺少主语、宾语或表语，且先行词为“near-Earth planets”，所以应用关系副词where。故填where。
82．
考查现在分词和省略句。句意：当结合人类和机器人的探索方法时，我们将使用技术来提高我们观察和发现新知识的能力。在when引导的状语从句中，从句和主句主语相同，所以省略从句的主语和be动词。动词combine意为“结合”，和主语we构成主动关系，所以应用现在分词。故填combining。
83．
考查不定冠词。句意：火星一直是探险家的灵感源泉。source意为“来源”，为可数名词，此处为第一次提到，所以为泛指，应用不定冠词。故填a。
84．
考查连词。句意：机器人任务已经找到了水的证据，但地球以外是否存在生命仍然是个谜。“whether life exists beyond Earth still remains a mystery”和“Robotic missions have found evidence of water”构成转折关系，且空格后没有逗号，所以应用连词but。故填but。
85．
考查现在完成时的被动语态。句意：到目前为止，机器人任务已经证明火星具有与地球相似的特征。根据So far可知，此处应用现在完成时。根据“by robotic missions”可知，此处应用被动语态。主语the evidence为第三人称单数。故填has been shown。
86．
考查过去分词。句意：运输探险者所需的技术和空间系统将鼓励以创造性的方式应对挑战。动词require意为“要求”，和谓语之间没有连词，和逻辑主语“The technology and space systems”构成被动关系，且动作已完成，所以应用过去分词作后置定语。故填required。
87．
考查名词复数。句意：前往火星旅行并学习如何在那里生活的挑战将鼓励各国共同努力，实现这样一项雄心勃勃的事业。根据“work together”可知，此处是指很多国家，所以应用名词复数。故填nations。
88．
考查形容词。句意：国际空间站表明，合作的机会将突出我们的共同利益，并提供一个全球性的社区意识。修饰名词sense应用形容词作定语。形容词global意为“全球性的”。故填global。
NASA will use the International Space Station as a stepping stone for the journey ahead. They will prepare astronauts for the human exploration. Explorers may visit near-Earth planets, 81． we may get answers to the questions humans have always asked. Visiting an asteroid (小行星) will prepare for the first humans to step on Mars.
Robotic exploration continues to deliver answers about our Universe by visiting far-off destinations. When 82． (combine) human and robotic exploration methods, we will use technology to increase our ability to observe and uncover new knowledge. Mars has always been 83． source of inspiration for explorers. Robotic missions have found evidence of water, 84． whether life exists beyond Earth still remains a mystery. So far, the evidence that Mars has characteristics similar to Earth’s 85． (show) by robotic missions. Humans can build upon this knowledge and look for signs of life on Mars, resulting in research and methods that could be applied here on Earth.
A mission to our nearest neighbor provides the best opportunity to show that humans can live beyond the Earth. The technology and space systems 86． (require) to transport explorers will encourage creative ways to address challenges. The challenge of traveling to Mars and learning how to live there will encourage 87． (nation) to work together to achieve such an ambitious undertaking. The International Space Station has shown that opportunities for cooperation will highlight our common interests and provide a 88． (globe) sense of community.
81．where
82．combining
83．a
84．but
85．has been shown
86．required
87．nations
88．global
【分析】
这是一篇说明文。美国宇航局将把国际空间站作为未来旅程的踏脚石，文章对此进行了介绍。
81．
考查定语从句。句意：探险家可能会造访近地行星，在那里我们可以得到人类一直问的问题的答案。在非限制性定语从句中不缺少主语、宾语或表语，且先行词为“near-Earth planets”，所以应用关系副词where。故填where。
82．
考查现在分词和省略句。句意：当结合人类和机器人的探索方法时，我们将使用技术来提高我们观察和发现新知识的能力。在when引导的状语从句中，从句和主句主语相同，所以省略从句的主语和be动词。动词combine意为“结合”，和主语we构成主动关系，所以应用现在分词。故填combining。
83．
考查不定冠词。句意：火星一直是探险家的灵感源泉。source意为“来源”，为可数名词，此处为第一次提到，所以为泛指，应用不定冠词。故填a。
84．
考查连词。句意：机器人任务已经找到了水的证据，但地球以外是否存在生命仍然是个谜。“whether life exists beyond Earth still remains a mystery”和“Robotic missions have found evidence of water”构成转折关系，且空格后没有逗号，所以应用连词but。故填but。
85．
考查现在完成时的被动语态。句意：到目前为止，机器人任务已经证明火星具有与地球相似的特征。根据So far可知，此处应用现在完成时。根据“by robotic missions”可知，此处应用被动语态。主语the evidence为第三人称单数。故填has been shown。
86．
考查过去分词。句意：运输探险者所需的技术和空间系统将鼓励以创造性的方式应对挑战。动词require意为“要求”，和谓语之间没有连词，和逻辑主语“The technology and space systems”构成被动关系，且动作已完成，所以应用过去分词作后置定语。故填required。
87．
考查名词复数。句意：前往火星旅行并学习如何在那里生活的挑战将鼓励各国共同努力，实现这样一项雄心勃勃的事业。根据“work together”可知，此处是指很多国家，所以应用名词复数。故填nations。
88．
考查形容词。句意：国际空间站表明，合作的机会将突出我们的共同利益，并提供一个全球性的社区意识。修饰名词sense应用形容词作定语。形容词global意为“全球性的”。故填global。
