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人体的“警卫兵”——免疫系统人体免疫系统是人最重要的保卫系统。因为有了它,人体才能抵御病原菌的侵犯。它具有高度的辨识能力,通常能精确识别自身和异己物质,使
The body’s “guard” - the immune system The human immune system is one of the most important defense systems. Because of it, the human body can resist the invasion of pathogens. It has a high degree of identification, usually accurate identification of their own and alien substances