Tube-current is the all-important parameter of the X-ray machine; it affects the reciprocity between the X-ray and the others material.

管电流是X射线机中非常重要的参数，它影响X射线与其它物质的相互作用。

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This evidence and the findings of public-goods experiments led the anthropologists to conclude that acceptance and rejection were strongly linked to feelings of fairness and reciprocity in addition to material benefits.

ECONOMIST: Human behaviour