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问题 单项选择题

（）定位方法是将GPS接收机集成在移动台里，在全码域范围内搜索可以使用的GPS卫星以完成定位操作，并直接将结果报告给网络。

A.传统GPS定位方法

B.相对定位/差分定位DGPS

C.网络辅助的GPS定位方法AGPS

D.AFLT

答案

参考答案：A

问答题 论述题

影响沉淀溶解度的因素有那些？是怎样发生影响的？
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单项选择题

As viewed from space, the Earth’’s distinguishing characteristics are its blue waters and white clouds. Enveloped by an ocean of air consisting of 78% nitrogen and 21% oxygen, the planet is the only one in our solar system known to harbor life. Circling the Sun at an average distance of 149 million km (93 million miles), the Earth is the third planet from the Sun and the fifth largest planet in the solar system. Its rapid spin and molten nickel-iron core give rise to an extensive magnetic field which, coupled with the atmosphere, shields us from nearly all of the harmful radiation coming from the Sun and other stars. Most meteors burn up in the Earth’’s atmosphere before they can strike the surface. The planet’’s active geological processes have left no evidence of the ancient pelting it almost certainly received soon after it was formed. The Earth has a single natural satellite — the Moon.

What two factors help protect the Earth from radiation

A．Magnetic field and atmosphere.

B．Rapid spin and molten iron-nickel core.

C．The Sun and the Moon.

D．Blue waters and white clouds.
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