were (v.)youdaoicibaDictYouDict[were 词源字典]
Old English wæron (past plural indicative of wesan) and wære (second person singular past indicative); see was. The forms illustrate Verner's Law (named for Danish linguist Karl Verner, 1875), which predicts the "s" to "z" sound shift, and rhotacism, which changed "z" to "r." Wast (second person singular) was formed 1500s on analogy of be/beest, displacing were. An intermediate form, wert, was used in literature 17c.-18c., before were reclaimed the job.[were etymology, were origin, 英语词源]