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Vocabulary and Structure: Power electronics started with the development of mercury arc rectifier. Invented by Peter Cooper Hewitt in 1902, the mercury arc rectifier was used to convert alternating current into . A. three-phase power B. alternating voltage C. direct current D. high voltage
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【单选题】She _____ a bit of money every month for her son's future education. [ ]
A.
set about
B.
set off
C.
set out
D.
set aside
【单选题】I try to ______ a few minutes every day to do some exercises.
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set out
B.
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set up
D.
set aside
【简答题】一般确定两像片的相对位置有__________和__________两种方法
【单选题】We _________ some money every month in order to buy a computer.
A.
set out
B.
set up
C.
set aside
D.
set about
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