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【单选题】
现在人们认识到，极光一方面与地球高空大气和地磁场的大规模相互作用有关，另一方面有与太阳喷发出来的高速带电粒子流有关，这种粒子流通常被称为太阳风。由此可见，形成极光必不可少的条件是大气、磁场和太阳风，缺一不可。具备这三个条件的太阳系其他行星，如木星和水星，它们的周围也会产生极光，这已被实际观察到的事实所证明。 这段文字主要介绍的是：A.
太阳在极光形成中的作用
B.
形成极光的必备要素
C.
存在极光现象的行星
D.
人们对极光的观察和认识
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举一反三
【简答题】A.He doesn’t like to talk． B.He is a very kind man． C.He is friendly． D.He is not a pleasant person．
【单选题】He is a very____character he is never relaxed with strangers.
A.
self-confident
B.
self-conscious
C.
self-evident
D.
self-serving
【单选题】What can we inferred about the man?
A.
He is a very good worker before.
B.
He is badly in need of a job.
C.
He likes the job offered to him very much.
D.
He is an experienced job hunter.
【单选题】听力原文：W: He is a very able man, and he is a good translator. I've never seen any Dutch who can speak and write such good English. M: Do you mean your history teacher? He is surely a very learned man, n...
A.
He is from England.
B.
He is from Holland.
C.
He is from Denmark.
D.
He is from Spain.
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