本文阐述的是，铜及其合金精密零件氢气保护扩散钎接焊工艺问题。
This paper describes hydrogen shield diffusion braze welding technology for precise parts of copper and compound metal.
旅行者应遵从预防感染扩散的简单建议，如注意呼吸道卫生等，保护自己和他人。
Travellers can protect themselves and others by following simple recommendations aimed at preventing the spread of infection such as attention to respiratory hygiene.
旅行者只需遵从预防感染扩散的一些简单建议，即可保护自己和他人。
Travellers can protect themselves and others by following simple recommendations related to travel aimed at preventing the spread of infection.
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