疫苗也可以通过提供取自动物或人身上的B细胞来发挥同样的作用，从而使我们获得被动免疫。
A vaccine may also give us passive immunity by providing B cells taken from an animal or a human to play the same role.
跳蚤跳到动物或人身上，并藏在毛发里面。
蜱守候在草丛和灌木丛(不包括树)的顶端寻找动物宿主并通过爬而不是飞或跳转移至动物或人身上。
Ticks search for host animals from the tips of grasses and shrubs (not from trees) and transfer from there to animals or people. Ticks only crawl; they do not fly or jump.
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