penny是“便士”，ten a penny -- 字面上好像指的是：一个便士就能买到十个这样的东西；其实大家可以想象一下：如果在咱们的生活中，一分钱就能买到好多东西的话，那说明这些东西肯定会非常的便宜，分文不值，而且不是什么稀罕物，遍地都是！

【例句】
Nowadays "geniuses" appear to be ten-a-penny, along with "legends" and "great" players.
跟“传奇”和“伟大”球员一样，现在的“天才们”好像分文不值。

Small houses in the urban district are becoming very expensive, but the suburbs they are ten a penny.
市区小房的价格越来越高，可是在市郊却很便宜。