英文關鍵字
abstract
background
barb
barbed
barbwire
barrier
border
boundary
captivity
close
closeup
closed
danger
dangerous
defense
detail
fence
forbid
forbidden
freedom
ground
guard
imprisonment
iron
isolated
limit
line
metal
military
no
obstacle
prison
private
prohibit
property
protect
protection
razor
rust
rusty
safety
security
sharp
steel
stop
trespassing
up
war
warning
wire