Electric cars are powered solely by batteries.
The new hybrid vehicles switch between electricity and gasoline.
Government and private agencies have spent billions of dollars advertising the dangers of smoking.
The number of smokers is still increasing.
Some students go to a vocational school to learn a trade.
(b) Some students go to college to earn a degree
(a) Education in a free society teaches children how to think. (b) Education in a dictatorship teaches children what to think.