单项选择题

A．They don’t need conventional signs and symbols.
B．They only require a receiver in communication.
C．The distance between communicators can’t be too long.
D．They are not restricted in time and space.
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单项选择题
A．It will confine us to the four walls.B．We will have unlimited freedom.C．The rich will be even richer.D．Education will be widely spread.
A．It will confine us to the four walls.
B．We will have unlimited freedom.
C．The rich will be even richer.
D．Education will be widely spread.
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