In the future the energy of the sun, wind, sea and the heat of underground waters will be used on a large scale. these are the so-called "free" energy sources. they will be utilized only when they are more profitable than the traditional ones because their exploitation is usually much more expensive than energy supply from large electric power stations which run on coal or nuclear fuel. выпишите прилагательное в одной из степеней сравнение. укажите три степени сравнение данного прилагательного и переведите его.
profitable - more profitable - the most profitable
прибыльный - более прибыльный - самый прибыльный
more expensive
expensive - more expensive - the most expensive
дорогой - дороже - самый дорогой