Cigarettes are not only packed with cancer-causing chemicals - they also disarm the lungs' natural defense system.

香烟不仅仅含有致癌的化学物质，同时破坏肺天然的保护系统。

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Or, you can see them as the body's natural defense system.

不过你也可以把它们看成是身体的自然免疫系统。

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Or, you can see them as the body 's natural defense system.

或者，你也可以将它们看作是身体的自然防御系统。

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