VOA慢速英语:Future of Air Travel: Electric Planes and Flying Cars

hub – n. airport or city through which airlines send most of their flights

sustainable – adj. able to be used without being completely used up or destroyed

hybrid – n. something formed by combining two or more things

propulsion – n. force that pushes something forward

concept – n. created to test or show an idea or design

capsule – n. small container that can be separated from other pieces