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【简答题】
因励磁电流的不同,电磁铁分 、 两大类。
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皮皮学刷刷变学霸
举一反三
【单选题】What is the author's purpose in quoting 'Of course, we can not imagine a life without any friend'?
A.
To show his sympathy for those who hasn't got any friends in life.
B.
To introduce the topic of the quality and quantity of friends.
C.
To disagree with the finding from the research.
D.
To show the author's surprise when heating the finding.
【单选题】I型呼吸衰竭最主要的发生机制是