
【名词&注释】
继电器(relay)、电磁铁(electromagnet)、机械能(mechanical energy)、奥斯特(oersted)、第一人(first man)、电流的磁效应
[单选题]我国有文字可考的历史始于
A. 夏朝
B. 商朝
C. 秦朝
D. 东晋
查看答案&解析
举一反三:
[单选题]29. Ann didn't go back home because__________
A. she didn't want to
B. she was too busy to go home
C. she didn’t miss her father
D. she had to look for a job
[单选题]
A. either
B. too
C. again
D. instead
[多选题]关于电和磁,以下说法正确的是
A. 电动机工作时是将机械能转化为电能
B. 发电机工作原理是利用电流的磁效应
C. 电磁继电器的主要部件是电磁铁
D. 奥斯特是发现电和磁联系的第一人(first man)
[单选题]25. We can find ________under Lily's bed.
A. a backpack
B. some flowers
C. a basketball
D. a baseball
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