If those who run public transportation systems hope to make them greener in the future, they'll have to come up with solutions that are both energy efficient and effective.
# If those who run public transportation systems hope to make them greener in the future, they'll have to come up with solutions that are both energy efficient and effective.
# If those who run public transportation systems hope to make them greener in the future, they'll have to come up with solutions that are both energy efficient and effective.
#If those who run public transportation systems hope to make them greener in the future, they'll have to come up with solutions that are both energy efficient and effective.