请大家帮帮忙啊。。。这个问题颠覆了我对现在完成时的理解。。

萧尧

10、Carnivorous mammals can endure what would
otherwise be lethal levels of body heat because they
have a heat-exchangenetworkwhich kept the brain
from getting too hot.

which kept

that keeps

which has kept

that has been keeping

having kept

A Kept is the wrong tense.
B Correct. The verb keeps indicates a current
situation and is consistent with the other
verbs in the sentence. The sentence is clear
and concise.
C Mistaken 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-exchangenetwork
mayno longer have this effect.
D Has been keeping is the wrong tense.
我理解的现在完成时是：过去发生，持续到现在，并且对现在产生影响。可是与C的红字说法部分相悖啊。大家给我解答一下好不好？

rain424124

为什么是过去发生。。。

miss绿光

顶起，不明白OG这里的解释~

longwayahead

我选的是B我觉得是陈述一般客观事实

yiayia

对现在完成时有情况：
1.means one action that started in the past but countinue into the present, or remain true in the present.
2.sometimes, means that the action is definitely over, but its effects still revelent t othe present moment.
这两种情况用在C选项都是可以，所以OG解释用 may no longer
关键在于和longway说的一样，这题是陈述一般事实，和无论现在还是过去，或者未来都没有关系，这一事实一直存在，采用一般现在时来描述。

hlaboratory

窃以为是称述一般事实，且从语法规则上都是一般现在时，也没有必要用完成时。

而且从解释看，我个人认为一般完成时需要存在一个先后顺序的时间概念，而这到题并不存在一个严格的时间概念。