a dime a dozen
非常普遍或容易得到的；无价值或不重要的
口语·形容事物很普通或廉价
英文释义
something that is very common or easy to obtain
例句
In this city, coffee shops are a dime a dozen, so you can find one on every corner.
典故来源
源自美国19世纪，当时一毛钱可以买到一打鸡蛋等便宜商品，比喻东西很常见、不值钱。