A wildlife expert predicts that the reintroduction of the caribou into northern Minnesota would fail if the density of the timber wolf population in that region is more numerous than on wolf for every 39 square miles.
ETS explains that teh main clause must use the future tense, (the reintroduction of caribou) will fail, not the conditional "would fail".
我觉得如果用would的话是种虚拟语气的感觉,如果这样的话,那后面的is more numerous中的is就应该变成were了吧?(忘记将来时态虚拟语气的表示了,不过肯定不是is就是了.) 而且这里说的是科学家认为will fail if the density of the timber wolf population in that region is more numerous than on wolf for every 39 square miles. 这个是一个理论,是可能发生的.是在陈述状况.不知道这样回答LZ想的明白么?总之OG说的没错,从is 推出用will