单项选择题

Which of the following does an astronomical time clock do？（）

A.Determines the ambient light at night with a photocell.
B.Calculates sunset and sunrise times based on geographical area.
C.Determines the start and end of each of the seasons.
D.Synchronizes the local time displayed with the official world time.

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单项选择题Wiresthatareinstalledinairreturnsaboveaceilingmustbe（）

A.fire proof
B.fiberglass coated
C.plenum rated
D.teflon coated

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A.Directly to the left and right and slightly in front of the listener
B.Directly to the left and right and slightly behind the listener
C.Above and behind the listener
D.Directly behind the listener

单项选择题Ifthespeakersinaninstallationareoutofphase，thismeansthat（）

A.the subwoofer is at the wrong angle.
B.the front and rear speakers are reversed.
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D.the angle of the speakers are incorrect.

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A.Unshielded twisted pair
B.RJ-59
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单项选择题Whichofthefollowingisthecorrectsignalflowforananalogmulti-roomaudiosystem？（）

A.Source，Volume Control，Speaker，Amp
B.Source，Amp，Volume Control，Speaker
C.Amp，Source，Volume Control，Speaker
D.Speaker，Amp，Volume Control，Source