Wires that are installed in air returns above a ceiling must be（）

单项选择题Whichofthefollowingistherecommendedplacementoftherearsurroundspeakersina5.1surroundinstallation？（）

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.
C.the polarity of the speakers are reversed.
D.the angle of the speakers are incorrect.

单项选择题WhichofthefollowingcablingwouldbeMOSTcommonlyusedwithdigitalvolumecontrols？（）

A.Unshielded twisted pair
B.RJ-59
C.16/4 solid conductors
D.Speaker Wire

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

单项选择题WhichofthefollowingisthestandardaspectratioforHDTV？（）

A.2.35：1
B.4：3
C.1.33：1
D.1.78：1