生活口语习语大全O-6：once in a blue moon 极为罕见(mp3和文本下载)

脱口说英语口语生活习语

O-6：once in a blue moon 极为罕见

A:The river is much higher than the ground.
A:河比地高得多。

B:How dangerous!
B:多危险呀！

A:Yes, it is.
A:是呀。

B:What if the river overflowed its bank?
B:河水要是涨过了岸，怎么办？

A:That would be disastrous.
A:那可遭殃了。

B:The whole city will get flooded?
B：整个城市就会被水淹了？

A:Of course. But that happens only once in a blue moon.
A:就是，不过那百年也不见得会遇上一次。