It is unlikely that the united states will have further turning points in environmental policy, as most important issues have already been addressed. t or f

This statement is false.
It is not true that most important issues have been addressed - this is very wrong because not much attention is being paid to global warming, as well as other pressing issues. And even if it were, America is always trying to correct the wrongs in the world, so there will surely be more turning points in the future.