See? “By” originally means “bye” or byway. That’s why, in fact, some people still spell “by the by” as “by the bye”. By the way, “that is by the by or bye” in this sense (secondary) is an idiom that ...
例句 The oldest leather artefact found so far is a 5,500-year-old shoe from a cave in Armenia, but paintings in Egyptian tombs show that, 7,000 years ago, leather was being turned into all manner of ...