因果关系是一件事(原因)和第二件事(结果)之间的关联，其中第二件事被认为是由于第一件事所产生的结果。

Causality is the relationship between an event (the cause) and a second event (the effect), where the second event is understood as a consequence of the first.

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事件的因果关系难以被人们搞清楚的一个复杂因素是，几乎世界上的任何一个事件，从来就不是仅有单单一个原因造成的。

One factor that makes causes so hard to think about is that there is never just one cause of any event in the world. There are many reasons why there are many causes.

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事件的原因（事件因果关系）是理解该事件的重要因素。

The cause of an event -- event causality -- is an important factor in understanding that event.

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