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.

这个是怎么算的，我只能看出要求的人数是总人数的百分之三

这题除了试数还有什么好方法吗？如果试数的话，如何快速找到适合的数呢？

条件二说的是每一项Sn都大于5吗？，但是n/（n+1）不是小于1吗？我不知道该怎么理解和使用该条件

条件2是要把对角线为8时的情况算出来吗？如果不是，应该怎么判断吗？另外五边形的面积应该怎么算呢？

这题怎么思考？还有绝对值不等式的考点有哪些啊

B单独不能成立吗？k=7带入不等式中，不是可以限制m和n的范围吗

题干不是已经能排出+和➗好了吗？因为此时式子没有意义。那两个条件为什么不能单独成立呢？这题的逻辑是什么

条件2为什么单独不成立？B做了超过50%，说明B比A效率高，那么3小时内可以完成

已知由一个符号@表示的加减乘除中的一一个符号。如果a@ (-a) =0,那么a=0.问:以下条件能否判断符号@是加减乘除中的哪一个?条件1).其中a@(a@a)=0, a=0;条件2).其中a@(b@c)=(a@b)@c. 答案：E

老师这道题和后面你讲的6和4的例子没看懂！