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雷达卡
Unit 3 Science and nature
能力提升题组训练 (A)
Ⅰ . 阅读理解
Many years ago,people relied on the sun,the moon and stars to find their way around.Later,the compass
was introduced.And now,we have satnav ( 卫星导航 ) systems to guide us.A satnav system uses groups of
satellites to show the user ’s location. They send information to a receiver,such as a smart phone,to
show us where we are.
The earliest built satnav system is the Global Positioning ...
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