【新编英语教程】（第一册）Unit4 资源(4/6)

英语自学网

注意首字母的大小写，不含标点符号
____1___, wood, and coal. There fuels have been formed over many centuries from plants. People burn them to produce heat and to create power for machines. ___2____, too. And electricity produces light, heat, and sound energy. ___3___, electric power operates many kinds of equipment, tools, and machines, ___4____.There is also solar energy in oil
Coal and oil are used to produce electrical energy
In addition
which make work easier