Then he had a machine that granted each pigeon one piece of corn every fifteen seconds; that's very, frustratingly slow for a hungry pigeon to get one piece every fifteen seconds.

他们设计了一个能保证,每隔15秒给鸽子喂一玉米粒的装置,对饥饿的鸽子来说是杯水车薪,每15秒才只有一粒玉米

耶鲁公开课 - 金融市场课程节选

Like every few blocks here, there's another beautiful children's park,

这里每隔几个街区，就有一个漂亮的儿童公园。

最美丽的公园 - SpeakingMax英语口语达人