英文關鍵字
antenna
broadcast
broadcasting
cell
cellular
chief
communication
connection
danger
frequency
global
gsm
guard
helmet
industrial
industry
information
inspector
internet
man
metal
microwave
music
network
phone
protection
radio
receiver
safeguard
safety
shape
signal
sky
spy
spying
station
steel
surveillance
technology
television
thief
tower
trace
transmission
transmitter
undercover
worker