Day 8

英文重現

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.第一個句子中，“which”引導非限制性定語從句，修飾“arboreal snakes”，“which”在從句中作主語，指代被其修飾的先行詞“arboreal snakes”，從句有兩個并列的謂語

“dwell”和“assume”。

2.第二個句子中，“circulated to the tail of the snake”是過去分詞短語作后置定語，修飾前面的“blood”，句子的謂語應該是“travel”。

3.有心的考生可能會問：謂語為什么是“travel”，而不是“travels”呢？明明主語

“blood”是不可數名詞啊。這是因為在“demand, insist, ask, require”等表示（或暗含）“要求”類的動詞之后的賓語從句需要用虛擬語氣，從句中的謂語要用“should +動詞原形”（“should”可以省略），而從這個知識點我們也可以判斷前面的“circulated”不是謂

語動詞，而是分詞作定語。

在這里跟大家總結一下如何區分過去分詞和過去式：

a. 看名詞是主動發出還是接受這個動作：主動發出為過去式，接受為過去分詞。

b. 看動詞是否及物，如果該動詞為不及物動詞，那么它一定是個過去式。

c. 動詞后面如果有“by…”，那么這個動詞就是過去分詞作后置定語。

4.“a problem”是前面整個句子“Such a location requires that blood circulated to the tail of the snake travel a greater distance back to the heart”的同位語，后面的“solved by another adaptation”是過去分詞作定語，修飾“a problem”。

詞義辨析

參考翻譯

但是，對于居住在樹上并且經常采用垂直姿勢的樹蛇來說，從心臟到頭部的平均距離可以短到整個身體長度的15%。這種位置要求循環到蛇尾的血液得流經很長的距離才能返回到心臟——一個能夠被另外一種適應性改變解決的問題。

實戰演練

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.

(C) A decrease in blood pressure at the snake's midpoint when it is tilted at various angles with its head up.

(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

根據“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”與題目中的“in close proximity”對應，“problem”對應題目中的“disadvantage”，因此關鍵是要理解“problem”的內容。原文中“problem”是其前面句子“Such a location requires…back to the heart”的同位語，所以重點看“requires + that從句”這部分，意思是“循環到蛇尾的血液得流經很長的距離才能返回到心臟”，與此對應的只有選項E“血流到尾部或從尾部流到心臟所需的努力更多”。

選項A“蛇調節流到腦部的血的效率降低”錯誤，“流到腦部的血”與原文“返回到心臟”不一致；選項B“在不損失流到腦部的血的前提下，蛇能夠采取的空間方位數量下降（即只能采取某些姿勢）”、選項C“當蛇昂著頭向不同角度傾斜時，蛇中部的血壓

下降”，以及選項D“蛇低著頭向不同角度傾斜時，血液更容易在蛇的腦部積聚”在文中都未提及。