2015年9月20日，我国新型运载火箭长征六号成功将20颗微小卫星送入太空，此次发射成功，标志着长征系列运载火箭家族再添新成员，而且创造了中国航天一箭多星发射的新纪录．中国在空间技术上最早的突破是（    ）

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Dear Ricky,
    How are you ____ on? Thanks very much for sending me the pictures and the English reading materials. From the pictures I can ____ that your school looks very beautiful. The reading materials are very useful and ____. I can learn a lot from them.  Some stories are so interesting that I like them very much.
    Now I don't have ____  time for my hobbies. I am busy getting ready for the coming exams. I’m working hard at all my lessons because I want ____ a better result.
    I'm looking forward to hearing from you soon.
Yours,
Wu Ming

对我国危害和影响最大的地质灾害是（    ）