A signal derived from a controlled function and returned to the initiating point is called

A good advertising program tells potential customers the benefits derived from the use of products.（)

From thousands of kilometers above our earth, a communications satellite ______ a signal f

______ conveys a signal of desired rudder angle from the bridge and activates the power un

A yellow signal，floating in the air from a parachute，about 100 meter above the water，indic

theory holds the opinion that a linguistic sign derives its meaning from that which re

Referential theory holds that a linguistic sign derives its meaning from that which re