妖しい
怪しい
alarm
angle
building
burglar
cam
camera
cameras
cctv
city
clean
clear
control
copy
danger
defense
digital
electronic
equipment
guard
lens
looking
monitoring
nobody
observe
outdoors
private
protect
protection
record
safe
safety
secrecy
secretly
secure
security
serene
space
sphere
spy
spying
surveillance
system
technology
video
view
wall
watching
white
yellow