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.

第8题的思路是以BC为底，从F向BC做垂线，跟BC交点H，FH为三角形FBC的高。然后三角形BFH跟三角形BDC相似，h：30=BF：BD，但是BF长度未知，望老师解答。

求问此题：DS：一个矩形地毯问面积是否大于160？ 条件1：对角线>21 条件2：至少有一条边大于8 谢谢！

求问此题的详细解法。谢谢老师~！

下面那个圆的半径我求不出来。请老师答疑！谢谢！

请问这道题是选E吗（答案我给忘了）？一个数N是否能被4！的三次方整除 1）这个数能被6！的二次方整除 2）这个数能被9！整除

5^500 + 5^501 + 5^502 + 5^503 最大的质因子是多少？求具体解法！谢谢老师！

求问此题：一个正方体，选三条不在同一顶点的棱涂成红色，问有几种方法？我的计算过程是C(12,1)*C(7,1)*C(2,1)=168.不知道思路正确与否，请老师答疑解惑。谢谢！

此题求解：DS：3个数，问中位数是否大于平均数？ 条件1：最大数和最小数之和大于中位数； 条件2：最大数=450+平均数，最小数=平均数-150 谢谢！

一个正方体，选三条不在同一顶点的棱涂成q红色，问有几种方法？ 请may回答 我算的是（ C3 12 ）-8