One hundred years ago, the invention of the automobile (1) (view) as a great step. Today autos (2) (not consider) such wonderful machines. They are the cause of a number of environmental problems. The most serious is pollution. Many chemicals including large amounts of carbon dioxide (C02) (3) (release) into the atmosphere as a result of gasoline and diesel fuel burning. People should (4) (encourage) to use motor vehicles less. If it (5) (achieve), the amount of C02 produced by cars and trucks (6) (limit). Public transport should (7) (make) attractive and convenient. The number of cars on the roads can (8) (limit) by charging drivers fees and taxes. Lately, fees (9) (charge) for going downtown in some countries. These fees keep people from driving unnecessarily. The money (10) (use) for public transportation.
Pollution can (11) (reduce) by using nonpolluting fuels. There are several nonpolluting fuels already available. One is natural gas. In some cities of the USA older buses and vans (12) (replace) with vehicles that burn natural gas. Electricity is another less polluting source of energy. The "hybrid car" running on gasoline and electricity already (13) (put) on the market in many countries.
Of all the new fuels, hydrogen (14) (consider) "clean". Hydrogen (15) (believe) to be the fuel of the future.