As viewed from space, the Earth’s distinguishing characteristics are its blu

游客2024-01-02  30

问题     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. [br] Which of the following helps to create the Earth’s magnetic fields?

选项 A、Its blue waters.
B、Its nitrogen atmosphere.
C、Its molten metal core.
D、The Moon.

答案 C

解析 见文中第四句:Its rapid spin and molten nickel-iron core give rise to an extensive magnetic field which,…地球迅速的自转以及其熔融的镍铁地核引发了广泛的磁场……由此可知地球的磁场是借助于其自身的自转及其熔融的地核引发的,因此答案为C。
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