原文的意思是,drop restriction can allow others to recover
我觉得做逻辑题不能靠胡思乱想
D很清楚:goose增加时,她们就到别的地方去了,因此,既不会对现有地方的鸟造成威胁,也不会对他们才去的地方的鸟造成威胁(snow geese have recolonized wintering grounds that they had not used for several seasons),同时原文又说:Some species of Arctic birds are threatened by recent sharp increases in the population of snow geese