習語口語對話大全(MP3+中英字幕) 第247期:once in a blue moon
once in a blue moon
A:The river is much higher than the ground.
A:河比地高得多。B:How dangerous!
B:多危險呀!
A:Yes, it is.
A:是呀。B:What if the river overflowed its bank?
B:河水要是漲過了岸，怎麼辦?A:That would be disastrous.
A:那可遭殃了。B:The whole city will get flooded?
B：整個城市就會被水淹了?A:Of course. But that happens only once in a blue moon.
A:就是，不過那百年也不見得會遇上一次。
