托福考试

【单选题】
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[*] Why does the professor say this:
A．To explain how the auroras are electrical in nature
B．To change the subject to something more interesting
C．To encourage the student to observe the auroras
D．To imply that the auroras contribute to global warming
网考网参考答案：A
网考网解析：
[解析] Why does the professor say this: "As you know, an electrical generator has two components: a conductor and a magnetic field. To generate electricity, the conductor has to move across the field to produce a force. With the auroras, the conductor is the solar wind carrying a stream of charged particles." The professor’s purpose is to explain how the auroras are electrical in nature. The student says it sounds kind of like electricity, and the professor responds by explaining how electricity is generated by the solar wind, carrying a stream of charged particles and moving across Earth’s magnetic field. (2.3) document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>