The drug has lost its potence by being exposed to moisture.

这药因受潮失去了效力。

《新英汉大辞典》

When not in use must be locking cap, exposed to moisture in the air may cause the curing in the container.

不用时必须锁紧瓶盖，暴露在有水分的空气中可能使其在容器中固化。

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The lid must be tightened immediately after use. Active chemicals inside the container may solidify when exposed to moisture in the air.

使用完毕请锁紧瓶盖，暴露在有水分的空气中可能使其在容器中固化。

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The problem is that calcium, magnesium and lithium are a bit fussy and chemically quite reactive and will oxidize or stop working if they are exposed to oxygen and moisture.

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They spiked droplets of human mucus with live flu virus, and then exposed it to air with varying levels of moisture.

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