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【单选题】
当他励直流电动机串入相同的制动电阻时,反接制动与能耗制动的初始制动电流之比约等于( )。A.
1/2
B.
1
C.
2
D.
3
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皮皮学刷刷变学霸
举一反三
【单选题】We can infer that current virtual reality devices ______.
A.
still need improving to create a perfect virtual world
B.
are already perfect to create a virtual world
C.
are unable to create a virtual world
D.
are harmful to users of virtual reality
【单选题】Which of the following statements about economic models is correct?
A.
Economic models are built to mirror reality exactly.
B.
Economic models are useful, but they should not be used for the purpose of improving public policies.
C.
Because economic models omit many details, they allow us to see what is truly important.
D.
Economic models seldom incorporate equations or diagrams.
【单选题】The book provides a concise analysis of the country’s history．
A.
clean
B.
perfect
C.
real
D.
brief
【单选题】Economic models
A.
are people who act out the behavior of firms and households so that economists can study this behavior.
B.
are usually detailed replications of reality.
C.
incorporate simplifying assumptions that often contradict reality, but also help economists better understand reality.
D.
are useful to researchers but not to teachers because economic models omit many details of the real-world economy.
【单选题】Economic models
A.
cannot be useful if they are based on false assumptions.
B.
were once thought to be useful, but that is no longer true.
C.
must incorporate all aspects of the economy if those models are to be useful.
D.
can be useful, even if they are not particularly realistic.
【单选题】Economic models
A.
are not useful because they omit many real-world details.
B.
are usually composed of diagrams and equations.
C.
are useful because they do not omit any real-world details.
D.
contribute very little to economists’ understanding of the real world.
【单选题】Some child ren stated that they used their unsupervised free time to perfec t their athletic skills, such as playing basketball
A.
GemmaGemma spent hours trying to perfect her technique spent hours trying to perfect her technique
B.
The treaty is far from perfect, but it is clearly the way forward.
C.
In English, the perfect is formed with "have" and the past participle of the verb.
【单选题】In the wife’s eyes, his _____ to their marriagelife is far from perfec
A.
requirement
B.
commitment
C.
participation
D.
reflection
【单选题】Which of the following statements about economic models is valid?
A.
Economic models are built to mirror reality exactly.
B.
Economic models are useful, but they should not be used for the purpose of improving public policies.
C.
Because economic models omit many details, they allow us to see what is truly important.
D.
Economic models seldom incorporate equations or diagrams.
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