white-footed mouse造句

• A factor helping the spread of lyme disease in the eastern united states , for instance , was the absence of former predators like wolves or wild cats that once kept down numbers of white - footed mice - a reservoir of the infection
  这些食肉动物的存在曾经很好地抑制了白足鼠的数量，而白足鼠则是莱姆病病原菌的携带者。而在美国其他一些地区，莱姆病其实算不上什么大问题。