此外，世卫组织很早就指出，流感病毒缺乏稳定性，可以迅速发生重大变异，因此难以预测其影响是否会维持中等程度。

WHO also noted, early on, that influenza viruses are unstable and can undergo rapid and significant mutations, making it difficult to predict whether the moderate impact would be sustained.

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研究人员们怀疑，冬季的低温、潮湿、紫外线等条件会增加病毒的稳定性，缩在屋子里的人们也一样会方便它的传播。

Researchers suspect that lower temperature, humidity, and ultraviolet light during the winter may increase viral stability; people huddling indoors may facilitate spread as well.

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认真选择下载网站。并不是所有的网站都对软件的稳定性、可用性、侦察功能和病毒进行测试。

Choose your download site carefully. Not all sites test software for stability, usability, spyware, and viruses.

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