第8题，主题题Oneof the questions of interest in the study of the evolution of spiders iswhether the weaving of orb webs evolved only once or several times. About halfthe 35,000 known kinds of spiders make webs; a third of the web weavers makeorb webs. Since most orb weavers belong either to the Araneidae or theUloboridae families, the origin of the orb web can be determined only byascertaining whether the families are related.
Recenttaxonomic analysis of individuals from both families indicates that thefamilies evolved from different ancestors, thereby contradicting Wiehle’stheory. This theory postulates that the families must be related, based on theassumption that complex behavior, such as web building, could evolve only once.According to Kullman, web structure is the only characteristic that suggests arelationship between families. The families differ in appearance, structure ofbody hair, and arrangement of eyes. Only Uloborids lack venom glands. Furtheridentification and study of characteristic features will undoubtedly answer thequestion of the evolution of the orb web.
8.
Theprimary purpose of the passage is to
(A) settle the question of whether orb webs evolvedonce or more than once
(B) describe scientific speculation concerning anissue related to the evolution of orb webs
(C) analyze the differences between the characteristicfeatures of spiders in the Araneidae and Uloboridae families
(D) question the methods used by earlier investigatorsof the habits of spiders（B）
(E) demonstrate that Araneidae spiders are not relatedto Uloboridae spiders
为什么不选A？是不是因为本文并没有对这个question给出明确的回答？只是在进行一些分析。
但是我又觉得B里面的那个speculation在文中没有体现。speculation是“推测”的意思吧？不能仅仅因为文中有assumption，就说全文都是在推测啊。 请高手指点迷津，谢谢
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发表于 2012-4-11 09:01:00
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