有时，污染物与紫外线可能减弱了两生类的免疫系统，创造了感染的条件，使其更容易被寄生虫入侵。

At other times, pollutants or radiation may set the stage for infection by weakening an amphibian's immune system and thus leaving the animal more vulnerable to a parasitic invasion.

youdao

有时，污染物与紫外线可能减弱了两生类的免疫系统，创造了感染的条件，使其更容易被寄生虫入侵。

At other times, pollutants or radiation may set the stage for infection by weakening an amphibian's immune system and thus leaving the animal more vulnerable to a parasitic invasion.

youdao