The spacing of the slats varies depending upon exposure to the sun.

立面条板间的间距并不相同，根据接触阳光的面积而改变。

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Patients who demonstrated to severe rhinitis symptoms upon exposure to ragweed were admitted to the study.

暴露于豕草而激发严重鼻炎症状并证实得到缓解的患者加入该研究。

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Upon exposure of the solid polymers to ultraviolet light the polymers tend leads to produce degradation or crosslinking.

在紫外光辐照下，高聚物的薄膜或纤维发生降解或交联反应。

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Upon exposure to water and oxygen, these minerals oxidize to form acid-, iron- and sulfate-rich drainage.

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Doses may be chronic or acute depending upon the duration of exposure.

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More broadly, the principle upon which immunisation is based - namely, exposure to a non-harmful version of the naturally occurring infection in order to induce a natural and protective immune response - can be seen to be a far more natural process than the drug- and surgery-based therapies most widely venerated as the main achievements of modern medicine.

BBC: 'The natural benefits of vaccines'