VOA慢速英语:蜻蜓透明牙齿之谜

transparent – adj. able to be seen through

reflecting – v. to move in one direction, hit a surface, and then quickly move in a different and usually opposite direction — usually + off

invisible – adj. impossible to see

enamel – n. the very hard outer layer of a tooth

hierarchy – n. a system in which people or things are placed in a series of levels with different importance or status

ingeniosity – adj. very smart or clever : having or showing ingenuity

attract – v. to cause (someone) to choose to do or be involved in something

beard – n. the long hair that grows on the chin of some animals