What are used for communication by two people by transmitting signals?
electricity satellites air phytoplanktons unidirectional telephones the Sun waves
A B C D E F G H
Loudspeakers then turn the signals into sounds.
telephones are used for communication by two people by transmitting signals
What are used for communication by two people by transmitting signals? (A) electricity (B) satellites (C) air (D) phytoplanktons (E) unidirectional (F) telephones (G) the Sun (H) waves