本题出自TPO 2 The Origins Of Cetaceans

原句案例

The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing.

词汇讲解

Backbone: n.脊骨，脊柱

Ambulocetus: n. 陆行鲸

Portion: n. 部分；一份

Even though: 即使; 尽管; 纵然

Fluke: n. 侥幸；锚爪 尾片

句子分析

句子结构

主句+分句1（宾语从句）+分句2（原因状语）

主句：

The structure of the backbone shows that 后接宾语从句

分句1：

Ambulocetus swam like modern whales by moving the rear portion of its body up and down

分句2：

Even though a fluke was missing. 由 even though引导的让步状语从句。 

参考翻译

但是，脊椎的结构显示，即使缺少尾片，陆行鲸通过上下移动其身体后部游动，这一点类似于现代鲸类动物。

原题解析

TPO Reading 2

10. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? (Sentence Simplification Question)
　　A.Even though Ambulocetus swam by moving its body up and down, it did not have a backbone.
　　B.The backbone of Ambulocetus, which allowed it to swim, provides evidence of its missing fluke.
　　C.Although Ambulocetus had no fluke, its backbone structure shows that it swam likemodern whales.
　　D.By moving the rear parts of their bodies up and down, modern whales swim in a different way from the way Ambulocetus swam.

本句指出：“虽然缺少fluke，A化石的背骨结构(the structure of the backbone)说明它正是像现代鲸类一样游泳。”A选项中“it did not have a backbone”与原句不符。BD选项中的“provides evidence of its missing fluke.”和“swim in a different way”在原句中找不到支撑，因此选择C。