19-12AS 阅读 Q27

传统理论无法令人满意的原因，可以根据文章结构定位到Paragraph 2, line 37 “polar gigantism had never been satisfactory explained”和题干要求对应。Line 37: “the trouble is that” 开始解释原因，说明了size and temperature之间的关系是 “not linear”非线性的（linear relationship: involving or exhibiting directly proportional change in two related quantities.）会有很多例外出现。所以呼应了D选项的 “not direct”。