[lemma=efficiency] [lemma="("] [lemma=□] □ □
[lemma=efficiency] [lemma="("] [lemma=amount] □ □
[lemma=efficiency] [lemma="("] [lemma="("] □ □
China needs to increase the efficiency ( amount of energy gained from each ton of coal burned ) and lessen the environment impact ( reduce emissions and waste ) of its coal-fired power plants .