The primary arc beads and the secondary arc beads are the important evidence for identification of the cause of fire during airplane electrical fire investigation.

一次短路电弧熔珠和二次短路电弧熔珠是飞机电气火灾原因鉴别的重要物证。

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The cause of the fire is not yet known.

火灾的原因尚不清楚。

《牛津词典》

The Paris prosecutor's office has opened an inquiry into "involuntary destruction by fire" indicating they believe the cause of the blaze was accidental rather than criminal.

巴黎检察官办公室对“火灾造成的非自愿破坏”展开了一项调查，这表明他们认为造成火灾的原因是意外事故，而不是犯罪行为。

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Indonesia is on the so-called Pacific Ring of Fire where several tectonic plates meet and often cause earthquakes.

VOA: standard.2009.09.03

The Scottish Fire and rescue Service said the cause of fire was not yet known.

BBC: Firefighters tackle blaze at Stirling Superglass factory

Fire investigators are searching for evidence to establish the cause of the fire, which broke out shortly before 1330 GMT.

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The westbound lanes of the bridge were closed as officers investigated the cause of the deadly fire, but the patrol said one lane of traffic reopened early Sunday.

NPR: Patrol: 5 Die In Limousine Fire On Calif. Bridge