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1·This will help to clear the respiratory passages to some extent and help expel mucus.

这有助于在一定程度上清除呼吸道通道并帮助排出粘液。

2·To expel air from the lungs suddenly and noisily, often to keep the respiratory passages free of irritating material.

从肺里突然的带有声响地排出气体，通常为了使呼吸道不受物质阻碍。

3·The main function of the respiratory system is to provide passages and room for gaseous exchange.

呼吸系统的主要功用是提供空气到肺的通路及气体交换的场所。