It is produced from radium in the decay chain of uranium, an element found in varying amounts in all rocks and soil.

它产生于铀衰变链中的镭，而铀是所有岩石和土壤中都能找到的一种元素，含量各不相同。

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When an element of the requirements chain changes, all the trace relationships are marked as suspect, as shown in Figure 28.

当需求链的某个元素发生变化时，所有的跟踪关系都会标记成可疑，如图28所示。

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They then traverse a substitution chain of element declarations or a type hierarchy to determine whether the element declaration satisfies the substitution or type derivation requirements.

然后遍历元素声明的代替链或类型层次结构，以决定元素声明是否满足代替或类型衍生要求。

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Once these forces were large enough, they gave incentives to each element in the chain--from the mortgage originator to the investment bank--to participate in and contribute to the bubble.

FORBES: Magazine Article

Coral reefs are an essential element in the food chain for coastal people, providing nurseries for fish and shallow hunting-grounds for fishing boats.

ECONOMIST: Pink coral into grey rubble

His mindfulness of the creative chain snaking from Woody Guthrie to Chuck Berry to Dylan and Lennon is a major element of what his albums are about, political and socioeconomic issues aside.

CNN: Review: 'Tracks' follow Springsteen at the top