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Day 8

英文重现

In arboreal snakes, however, which dwell in trees and often assume a vertical posture, the average distance from the heart to the head can be as little as 15 percent of overall body length. Such a location requires that blood circulated to the tail of the snake travel a greater distance back to the heart, a problem solved by another adaptation.

——GMAT OG 2015, Reading Comprehension, Passage 6

解析

1.第一个句子中，“which”引导非限制性定语从句，修饰“arboreal snakes”，“which”在从句中作主语，指代被其修饰的先行词“arboreal snakes”，从句有两个并列的谓语

“dwell”和“assume”。

2.第二个句子中，“circulated to the tail of the snake”是过去分词短语作后置定语，修饰前面的“blood”，句子的谓语应该是“travel”。

3.有心的考生可能会问：谓语为什么是“travel”，而不是“travels”呢？明明主语

“blood”是不可数名词啊。这是因为在“demand, insist, ask, require”等表示（或暗含）“要求”类的动词之后的宾语从句需要用虚拟语气，从句中的谓语要用“should +动词原形”（“should”可以省略），而从这个知识点我们也可以判断前面的“circulated”不是谓

语动词，而是分词作定语。

在这里跟大家总结一下如何区分过去分词和过去式：

a. 看名词是主动发出还是接受这个动作：主动发出为过去式，接受为过去分词。

b. 看动词是否及物，如果该动词为不及物动词，那么它一定是个过去式。

c. 动词后面如果有“by…”，那么这个动词就是过去分词作后置定语。

4.“a problem”是前面整个句子“Such a location requires that blood circulated to the tail of the snake travel a greater distance back to the heart”的同位语，后面的“solved by another adaptation”是过去分词作定语，修饰“a problem”。

词义辨析

参考翻译

但是，对于居住在树上并且经常采用垂直姿势的树蛇来说，从心脏到头部的平均距离可以短到整个身体长度的15%。这种位置要求循环到蛇尾的血液得流经很长的距离才能返回到心脏——一个能够被另外一种适应性改变解决的问题。

实战演练

One such adaptation is the closer proximity of the terrestrial snake's heart to its head, which helps to ensure circulation to the brain, regardless of the snake's orientation in space. The heart of sea snakes can be located near the middle of the body, a position that minimizes the work entailed in circulating blood to both extremities. In arboreal snakes, however, which dwell in trees and often assume a vertical posture, the average distance from the heart to the head can be as little as 15 percent of overall body length. Such a location requires that blood circulated to the tail of the snake travel a greater distance back to the heart, a problem solved by another adaptation. When climbing, arboreal snakes often pause momentarily to wiggle their bodies, causing waves of muscle contraction that advance from the lower torso to the head. By compressing the veins and forcing blood forward, these contractions apparently improve the flow of venous blood returning to the heart.

The author suggests that which of the following is a disadvantage that results from the location of a snake's heart in close proximity to its head?

(A) A decrease in the efficiency with which the snake regulates the flow of blood to the brain.

(B) A decrease in the number of orientations in space that a snake can assume without loss of blood flow to the brain.

(D) An increase in the tendency of blood to pool at the snake's head when the snake is tilted at various angles with its head down.

(E) An increase in the amount of effort required to distribute blood to and from the

snake's tail.

答案：E

答案解析

根据“disadvantage”和“location of a snake's heart in close proximity to its head”的意思可定位到文中的“In arboreal snakes, however, which dwell in trees and often assume a vertical posture, the average distance from the heart to the head can be as little as 15 percent of overall body length. Such a location requires that blood circulated to the tail of the snake travel a greater distance back to the heart, a problem solved by another adaptation”，“as little as 15 percent”与题目中的“in close proximity”对应，“problem”对应题目中的“disadvantage”，因此关键是要理解“problem”的内容。原文中“problem”是其前面句子“Such a location requires…back to the heart”的同位语，所以重点看“requires + that从句”这部分，意思是“循环到蛇尾的血液得流经很长的距离才能返回到心脏”，与此对应的只有选项E“血流到尾部或从尾部流到心脏所需的努力更多”。

选项A“蛇调节流到脑部的血的效率降低”错误，“流到脑部的血”与原文“返回到心脏”不一致；选项B“在不损失流到脑部的血的前提下，蛇能够采取的空间方位数量下降（即只能采取某些姿势）”、选项C“当蛇昂着头向不同角度倾斜时，蛇中部的血压

下降”，以及选项D“蛇低着头向不同角度倾斜时，血液更容易在蛇的脑部积聚”在文中都未提及。