Объяснение:
Превосходная степень:
1. The railroad is one of the most important means of transporation
the most important - превосходная степень
2. The fastest passenger trains in regular service travel at speeds of up to 185 mph
The fastest - превосходная степень
3. The world’s longest rail line is situated in Russia.
the longest - превосходная степень
Сравнительная степень:
1. Only ships carry heavier cargoes for longer distances; and on;y airplanes provide a faster means of public transporation than railroads do
heavier; faster - сравнительная степень
2. In test runs, these trains have reached speeds of more than 250 mph (400kmph)
more than - сравнительная степень