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.

r/t=2? 条件1：点（r,t）在（0，y）和（x，0）这条直线上，x和y不记得了 条件2：点（r,t）过（0，4）和（3，6）

K P M是三个正整数，问KP+M是奇数吗？ 条件1：KM+P是奇数 条件2：PM+K是偶数

DS：x/a+y/b=1，求该直线与x轴的交点？ 条件1：b=3 条件2：a=b

PS：m,p都是正整数，p是质数。x2-mx+p=0这个方程的根是正数。求m-p的值？ 选项有1，2，4之类。

DS：有12个人给老师买礼物，每个人至少出一块钱，总共出的钱是否不少于30 条件1：有一半的人至少出3块钱 条件2：4个人出的钱至少是出钱最少的人出的钱的5倍

DS：定义F(n)=n/k的余数，问K>10？ 条件1：F(n+32)=6 条件2：F(n+42)=8

PS：一个国家telephone exchange numbers有七个digits，但前三个digits都是一样的数字，例都是932打头。问至少需要多少个数字(minimum required number)可以组成282000个telephone exchange numbers？ 选项是：三个2十几的数字和两个2百几的数字。

DS：a,b,c,d互不相等，(a-c)/(b-d)=a/b吗？ 条件1：a/b=c/d 条件2：(a+c)/(b+d)=a/b

PS：the value of （4^8 - 8^16）/（2^12 – 4^16）

PS：讲一个租赁汽车的公司每一次购买会购买5辆新车，每次卖掉会卖掉3辆旧车，今年新增了14辆车，把每次买和每次卖都算做一次交易，问今年最少做了几次交易？