In retrospect, we should have insisted on checking his calculations, but it's easy to be wise after the event.回想起来，我们本该坚持检查他的计算结果，不过事后聪明倒是容易。It seems obvious now, but that's being wise after the event.现在事情看来显而易见，但这也是事后聪明。It doesn't help to be wise after the event.事后聪明是没用的。