英文關鍵字
background
barb
barbed
barbwire
barrier
blue
border
boundary
camp
crime
criminal
danger
dangerous
fence
forbidden
freedom
guard
iron
isolation
jail
line
lock
metal
military
nobody
penitentiary
police
prison
prisoner
private
protection
razor
safety
secure
security
sharp
sign
silhouette
sky
steel
sun
wall
war
warning
wire