[lemma=efficiency] [lemma="("] [lemma=amount] [lemma=of] □
[lemma=efficiency] [lemma="("] [lemma=amount] [lemma=of] [□]
[lemma=efficiency] [lemma="("] [lemma=amount] [lemma=of] □+
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 .