“以防万一”有很多种翻译的方法,要根据上下文来决定如何翻译。例如,可以翻译为just in caseIt may rain you'd better take an umbrella (just) in case (it does). 可能会下雨,你最好带一把雨伞,以防万一(下起雨来)。也可译为just to be on the safe sideAlthough the sun was shining, I took an umbrella (just) to be on the safe side.