If I say something happens " once in a blue moon, " it is uncommon, infrequent, rare.

如果我说某件事" once in a blue moon" ，那它就是不常见，发生，罕见。

During the 20th century, the East Anatolian Fault yielded little major seismic activity.

在20世纪，东安纳托利亚断层发生重大地震活动。

And this can help to explain the infrequency  of evacuation-based crushes.

这有助于解释基于疏散挤压事件发生原因。

Something that " seldom" happens doesn't happen very often.

“”发生事情不会经常发生。

Brachial plexus injury, pneumothorax and hemothorax are highly unlikely, but possible side effects of the surgery.

臂丛神经损害伤害，气胸和血胸发生，但是手术可能并发症。

Good choices rarely happen by accident.

好选择是偶然发生。

But total solar eclipses happen rarely because the moon's orbit is tilted five degrees.

但日全食发生，因为月球轨道倾度。

Reading is the only pleasure which fate has left me, and I miss little which passes in the world.

阅读是命运留给我唯一乐趣， 我错过世上发生事情。

Luckily, these bursts  rarely happen in our galaxy, but if one occurred, the consequences could be catastrophic.

幸运是， 这种爆发发生在我们星系中，但如果发生， 后果可能是灾难性。

There have been a lot of climatic changes during that time, and very few of them have occurred at this rate.

在那段时间里发生多气候变化，而且有以这种速度发生。

Svalbard has been hit by extreme rainfall in the past 10 years and seabird die-offs, something that used to happen infrequently, has become increasingly common.

过去 10 年，斯瓦尔巴特群岛遭受极端降雨袭击，过去发生海鸟死亡事件变得越来越普遍。

It can seldom happen, therefore, that a man of any considerable stock should quit the superior, in order to place himself in an inferior station.

因此，会发生这样情况：一个有相当地位人为让自己处于一个较低地位而放弃较高地位。

It seldom happens that any part of it is applied towards the improvement of land; or is so employed as to contribute, in any respect, towards increasing the revenue of the great body of the people.

发生它任何部分用于改良土地情况；或受雇于在任何方面有助于增加广大人民收入。

Great emergencies excepted, which would rarely occur in a society of which equality was the basis, a man could only be prepared to discharge the duties of public life, by the habitual practice of those inferior ones which form the man.

除在以平等为基础社会中发生重大紧急情况外，一个人只能通过形成他那些下等人习惯性实践来准备履行公共生活职责。