题目解析:
根据所考察的单词定位回原文中这一句:It was his dredge that was inadequate. Its opening was so small and the holes in the net so large that the dredge inevitably missed animals. 本句大意是:他的取样是不够的。因为他用的工具dredge开口太小,网上的孔又太大,导致这个东西肯定会漏下动物。inevitably意思是不可避免的。选项A是频繁地,选项B是必须地,选项C是不可预测的,选项D是不幸地,选项B最贴合inevitably的意思。选择B。