这道题正确答案是 B， 我一直觉得是D, 不是特别明白 B 答案为什么 说as effectively as sea snakes can? 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. 20. It can be inferred from the passage that which of the following is true of species of terrestrial snakes that often need to assume a vertical posture? (A) They are more likely to be susceptible to circulatory failure in vertical postures than are sea snakes. (B) Their hearts are less likely to be located at the midpoint of their bodies than is the case with sea snakes. (c) they cannot counteract the pooling of blood in lower regions of their bodies as effectively as sea snakes can. (d) the blood pressure at their midpoint decreases significantly when they are titled with their heads up.

请问数学老师 条件2为什么成立 谢谢老师

老师您好，这道阅读理解不会做，用定位的方法读了原文也没太懂为什么选D

文章的最后一句话回答了这个问题，也就是C选项，我不懂为什么正确答案是B

ken老师你好，这道题目我的思路是设97、98、99依次为a、b、c，根据题目得出b=C+y; b=a+x。条件1）x>y，可以得出a<c。 第二个条件不太懂。而且这道题目的开始的的less、 more in 1999，这些术语我转化成公式就浪费了半个小时，想问老师有没有更高效的解决办法？

请数学老师讲解下思路

麻烦老师给我讲解一下这一题，通过The body…was that of the man ，身体是那个男人的一部分，而不是身体是那个男人。这个点排除ABC. DE关于时态部分不是很清晰

请数学老师解答下第三个为什么不行

请数学老师帮我解答下，再讲下怎么画图 谢谢老师

麻烦老师给我辨析一下图1和图2，关于图1那题当时选错之后机构老师给我解答的是40 to 44 million years 是一个时间区间，不能用estimate at 因为 at 有精确到某个点的意味。那么图2的正确答案是不是因为3.47 billion years 是一个精确的年份所以要用 at 。。

麻烦老师给我解答一下这题，这题BUT后面主要想表达的核心语意是 家庭用电少于百分之一和家里面的电仍然是由蜡烛提供。我觉得B 顺着读下去也能表达这个语意，就是 我觉得AB 都能表达这个语意，关于两者的差异我不是很清晰 麻烦老师帮我辨析一下