句中“the nuclear explosions was occurred 不用被动语态 ”的原因?另外如何改正?

问题描述:

句中“the nuclear explosions was occurred 不用被动语态 ”的原因?另外如何改正?
This point is best illustrated with the example of Hiroshima and Nagasaki in Japan,the nuclear explosions was occurred (不用被动语态) nearly a half century later,the residual nuclear radiation badly has been endangered the natural ecosystems in the native.
核弹不启动怎么会自己爆炸,要是自己就能爆炸岂不是太恐怖了,所以我觉得是用被动合适,可批改就说应该是主动,到底是怎么算正确啊?

occur是不及物动词,不及物动词没有被动语态。