句子1
In a countercurrent exchange system, the blood vessels carrying cooled blood from the flippers run close enough to the blood vessels carrying warm blood from the body to pick up some heat from the warmer blood vessels; thus, the heat is transferred from the outgoing to the ingoing vessels before it reaches the flipper itself.
【难点解析】
本句的难点在于复杂的后置定语干扰了阅读，给我们理解句子带来了影响。在这个句子中就是现在分词短语carrying cooled blood…做了后置定语，造成了主语the blood vessels和谓语run被分割，后面接着出现了另一个the blood vessels carrying warm blood……，进一步加大了理解难度，让我们一时无法理清句子结构。找到这种后置定语，划分句子主干的时候直接忽视这种修饰性成分，句子的主要信息就变得非常清晰：
In a countercurrent exchange system, the blood vessels carrying cooled blood from the flippers[定语] run close enough to the blood vessels carrying warm blood from the body[定语] to pick up some heat from the warmer blood vessels; thus, the heat is transferred from the outgoing to the ingoing vessels before it reaches the flipper itself.
完成了句子主干划分之后，根据汉语的表述顺序，将后置定语往前放，这样整个句子的意思就出来了。
【成分划分】
并列句一
In a countercurrent exchange system, [状语] the blood vessels [主语] carrying cooled blood from the flippers [定语] run [谓语] close enough to the blood vessels [状语] carrying warm blood from the body [定语] to pick up some heat [状语] from the warmer blood vessels. [状语]
并列句二
The heat [主语] is transferred [谓语] from the outgoing to the ingoing vessels. [状语]
状语从句
It [主语] reaches [谓语] the flipper[宾语] itself. [状语]