VOA慢速英语:新的研究证实播云可以导致降雪

narrow down – phrasal verb. to make a group or list smaller

data – n. information or facts about something

boost – v. to increase of improve something

watershed – n. an area of land that separates waters flowing to different rivers, basins, or seas

simulated – adj. something made to look or behave like something real but which is not

revelation – n. an extremely pleasant surprise

certain – adj. completely sure of something