Task：The two graphs show the main sources of energy in the USA in the 1980s and the 1990s.
2. 注意重点数据的选取(max, min)
The two graphs show that oil was the major energy source in the USA in both 1980 and 1990 and that coal, natural gas and hydroelectric power remained in much the same proportions. On the other hand, there was a dramatic rise in nuclear power, which doubled its percentage over the ten years.
Oil supplied the largest percentage of energy, although the percentage decreased from 42% in 1980 to 33% in 1990. Coal in 1990 was the second largest source of energy, increasing its proportion to 27% from 22% in the previous decade. Natural gas, the second largest source in 1980 at 26%, decreased its share very slightly to provide 25% of America’s energy ten years later.
There was no change in the percentage supplied by hydroelectric power which remained at 5% of the total energy used. Nuclear power the greatest change: in 1990 it was 10%, twice that of the 1980s.
In conclusion, during the decade, the structure of energy resources remained, and the proportion of 3 aspects varied a lot, except natural gas and hydroelectric power.