機器
crude
donkey
drilling
drive
ecology
ecology problems
energy
environment
equipment
extracting
extraction
field
flowers
fuel
gas
gasoline
grasshopper
horse
horsehead
industrial
industry
jack
land
landscape
machinery
mechanism
metal
natural
nodding
oil
oil production
oil pump
overground
petroleum
piston
prairie
production
pump
pumping
pumpjack
reciprocating
rig
scene
sky
technology
thirsty
unit
well
yellow