GRE考试阅读辅导：长难句实例分析69

　　But the recent discovery of detailed similarities in the skeletal structure of the flippers in all three groups undermines the attempt to explain away superficial resemblance as due to convergent evolution ― the independent development of similarities between unrelated groups in response to similar environmental pressures.

　　但是，最近在所有这三类动物身上，对鳍肢的骨骼结构所存在的细致共同点的发现足以削弱这样一种企图，即把表面上的近似作为趋同进化所致的结果来将其解释掉。而所谓的趋同进化，是指在互不相关的生物群体之间，作为对类似的环境压力作出的反应，彼此独立的发展形成某些相同特征。

　　难句类型：复杂修饰

　　解释：读者大概也看出来了，本句的最大特点就是长，复杂修饰的长主语，复杂修饰的长宾语，中间以谓语undermines相连。修饰attempt的不定式中的to explain away something as意思是把某件事情当作后面的东西解释掉。本句在文中起到了一个极为重要的作用，后面有一道题专门对本句提问。现场这种句子能否顺利看懂，会对考生考试的分数起到直接影响。

　　意群训练：But the recent discovery of detailed similarities in the skeletal structure of the flippers in all three groups undermines the attempt to explain away superficial resemblance as due to convergent evolution ― the independent development of similarities between unrelated groups in response to similar environmental pressures.