英文關鍵字
ball
bearing
circle
circular
cylindrical
drive
engine
engineer
gear
gearbox
image
industry
mechanic
mechanism
roller
round
symbol
turn
wheel
英文關鍵字
ball
bearing
circle
circular
cylindrical
drive
engine
engineer
gear
gearbox
image
industry
mechanic
mechanism
roller
round
symbol
turn
wheel