英文關鍵字
abstract
aluminum
automobile
automotive
background
blue
chrome
circle
circular
closeup
construction
cutting
engine
engineering
equipment
exhaust
factory
illustration
industrial
industrialplant
industry
insulation
iron
line
machine
manufacturing
metal
metallic
muffler
pipe
pipeline
piping
power
product
production
profile
pump
reflection
round
saw
silencer
sky
stainless
steel
technology
tube
warehouse
work
worker
workshop