Their performance varies considerable, they are often idle, and then might have an occasional flurry of activity. For example, if their attendance is sporadic, they may have good attendance for a while, and then disappear unpredictably from time to time.
I think that number 3 is the answer you're looking for.
The television consists of four principles sets of parts, including the exterior or housing, the audio reception and speaker system, the picture tube, and a complicated mass of electronics including cable and antennae imput and output devices, a built-in antenna in most sets, a remote control receiver chips.
