单项选择题
Which of the following is the primary purpose of impedance matched volume control？（）
A.Maintains proper speaker phase B.Protects the amplifier from damage C.Protects the digital systems from damage D.Amplifies the speaker signal
单项选择题 Thenativeresolutionfor1080iis（）
单项选择题 Eachtimethedistancefromthespeakerisdoubled，volumedecreasesby（）.
单项选择题 AccordingtoOhm’sLaw，whichofthefollowingiscorrect？（）
