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 ...

美国白宫表示，特朗普于周六（2月1日）开始对美国三大贸易伙伴加拿大、墨西哥和中国加征关税。专家认为，此举或将进一步推高美国物价水平。