单项选择题
A.after two unplanned service calls. B.according to manufacturers specifications. C.when the device is becoming unreliable. D.every sixty days.
A.Xenon B.Halogen C.Incandescent D.Light Emitting Diode
A.Ignore both of them and decide what the real problem is. B.Set up a separate call for each problem. C.Have them duplicate the problem at the device. D.Ask a third person and see if the problem is the same thing.