budeyoudaoicibaDictYouDict[bude 词源字典]
"With a person or thing as subject and bare or to-infinitive. Was necessitated or obliged; should, must (with both deontic and epistemic force)", Late Middle English; earliest use found in Cursor Mundi: a Northumbrian poem of the 14th century. Originally a contracted variant of behoved, 3rd singular past indicative of behove; subsequently sometimes reinterpreted as a stem form showing invariant present and past forms.[bude etymology, bude origin, 英语词源]