VOA慢速英语:US Cities, States Step up for Climate Change

pledge – v. to formally promise to give or do (something)

absent – adj. not present at a usual or expected place

greenhouse gas – n. carbon dioxide and other gases that scientists have linked to rising temperatures in Earth’s atmosphere

renewable energies – n. any naturally occurring source of energy like solar, wind, biomass, tidal and hydroelectric power that is not taken from nuclear or fossil fuel.

emission – n. the act of producing or sending out something (such as energy or gas) from a source

stand in the gap – expression to take the place of a person who has fallen (sometimes a religious expression)

commercialization – n. to make something available to customers

looms – v. hangs over

enact – v. to make (a bill or other legislation) officially become part of the law

courageous – adj. very brave : having or showing courage