Carnivorous mammals can endure what would otherwise be lethal levels of body heat because they have a heat-exchange network which kept the brain from getting too hot.
10.Carnivorous mammals can endure what would otherwise be lethal levels of body heat because they have a heat-exchange network which kept the brain from getting too hot.
(A) which kept
(B) that keeps
(C) which has kept
(D) that has been keeping
(E) having kept CMistaken shift in tense: In this sentence the present tense expresses a timeless general principle; in contrast,has kept indicates a more definite context and time period and suggests that the heat-exchange network may no longer have this effect. 这句话里OG想说明什么东西?跪求指导。