所给词适当形式填空 develop produce die spit pollute

所给词适当形式填空 develop produce die spit pollute
Can you see the sign"No___"overthere?
Air____is the most serious problem at the moment
As we know,China is still a ____country in the world
Jane felt frightened as soon as she saw the____snake
Do you know America is one of the world's largest____of oil?