矿石样品放射性镭含量比岩石样品高19倍，为井下氡气的主要来源；
The content of radioactive radium in mineral was 19 times higer than that in rock and served as a chief source of radon.
矿石样品放射性镭含量比岩石样品高19倍，为井下氡气的主要来源；
The content of radioactive radium in mineral was 19 times higer than that in rock and served as a chief source of radon.
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