一、⑴美國過去被認為是一個還算環保的國家，為何他們的能源耗用如此高？⑵以下是京都議定書中 Article 12 中的一段話 “… may use the certifie “ d emission reductions accruing from such project activities to contribute to compliance with part of their qualified emission limitation and reduction commitments.” 請簡要說明這段話的含意。⑶請說明 Global Warming Potential。（25 分）