a dime a dozenWiktionary 原文词源说明With literal origins; now usually in the figuratively extended sense.释义（英文）形容词 Adjective(Australia, US, idiomatic) So common as to be practically or almost worthless.Used other than figuratively or idiomatically: see a, dime, a, dozen: sold at twelve (12) units per dime (10¢).词族相关词（2）dime storefive-and-dime