1. The non-conducting (а) material separating
(б) the plates is called dielutric.
2. Frequency-modulation presents an effective way of increasing
(г)
the signal-to-noise rate at the receiver.
3. We are always trying
(в) to improve the quality of the transmitted signal.
4. Flowing
(б) through a conductor the alternating current reverses its direction at regular intervals.