英文關鍵字
antenna
broadcast
broadcasting
cell
cellular
chief
communication
connection
danger
escape
frequency
global
gsm
guard
helmet
industrial
industry
information
internet
man
metal
microwave
network
property
protection
receiver
rope
safeguard
safety
shape
signal
spy
spying
steel
surveillance
technology
television
theft
thief
tower
transmitter
undercover
worker