注意首字母的大小寫，不含標點符號 ____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