In a modern three-phase A.C. synchronous brushes generator, the excitation winding is on the rotor. That means .

A．The generator need not excitation.

B．The winding on the rotor is for inputting excitation current.

C．There are three phase windings on the rotor.

D．The generator has no brushes.

[名词解释] Phase Shift相移

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[名词解释] 信号相位（Signal Phase）

[单选题]As an important phase in software development，software design is the continuation of software requirement analysis phase． (69) ．Ⅰ．software structureⅡ．software documentⅢ．software moduleⅣ．software procedureWhich of the following should be included in s

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