VOA慢速英语:Flip-Flop: Not Just for Your Feet

sandal – n. a shoe consisting of a sole strapped to the foot

switch – v. to shift to another electrical circuit by means of a switch : to make a change from one thing to another by turning or pushing a button or moving a switch, lever, etc.

circuit – n. the complete path that an electric current travels along

alternate – v. to place or do (different things) so that one follows the other in a repeated series

evolve – v. to change or develop slowly often into a better, more complex, or more advanced state : to develop by a process of evolution

literal – adj. in a way that uses the ordinary and usual meaning of a word : "Many words can be used both literally and figuratively."

figurative – adj. of words, language, etc. : used with a meaning that is different from the basic meaning and that expresses an idea in an interesting way by using language that usually describes something else : not literal

impression – n. the effect or influence that something or someone has on a person's thoughts or feelings

neutral – adj. not supporting either side of an argument, fight, war, etc.