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.

请问这道题c选项为什么不能用过去完成式？之前的“had installed”不也是过去完成式吗...怎么判断什么时候用过去完成时什么时候用现在完成时什么时间用一般过去时啊？

请问这道题e选项“that”表示了什么？

请问在这道题里面 to do和doing的区别是什么？

请问这道题为什么不可以用过去完成时？“its trunk”里面的its会不会被当成是aquatic animal而不是大象？“with”之后是不可以接整句吗？

请问这道题b、c为什么不对

请问这道题e选项错在哪里？

请问这道题为什么不能选e？

请问为什么c不对？that of是什么意思？

请问in which 和 where的区别是什么？哪个能指代抽象地点，哪个是实际地点？

D选项错的原因之一是说不应该用that they participate 请问这个错在哪里了？