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.
Carnivorous mammals can endure what would otherwise be lethal levels of body heat because they have aheat-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
小菜查了以前的帖子,但是都没有说这个问题的,所以我想请教大家~
1,has been doing,我个人认为是表示:从过去到现在,并且现在还在一直keeping~~,所以我不太懂D为什么错~ 2,E中的having kept的having怎么就imprecise了,我知道E中的kept时态有问题,但是having不太懂og意思~~
顺便粘出来一个关于现在完成时的解释,这点我能理解:
from 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.
时态确实是语法中比较难的部分。 对于此题楼主提出两个问题: 1·关于having been doing楼主说的不错,但是这里定语从句是用来表述network的性质、功能的,应该是一种一般状态的描述,当然这种一般状态确实是从过去就开始的,而且持续到现在还是,但是不能就因为这个原因说使用having been doing是对的,通常对这种一般状态的描述还是用一般现在时态比较好。 (关于时态,我也只是理解到这种地步了) 2·这个问题我还形成不了文字上的东西,不过关于having做后置定语修饰名词的分析在prep笔记上好像是有的,楼主可以翻阅一下。
时态确实是语法中比较难的部分。 对于此题楼主提出两个问题: 1·关于having been doing楼主说的不错,但是这里定语从句是用来表述network的性质、功能的,应该是一种一般状态的描述,当然这种一般状态确实是从过去就开始的,而且持续到现在还是,但是不能就因为这个原因说使用having been doing是对的,通常对这种一般状态的描述还是用一般现在时态比较好。 (关于时态,我也只是理解到这种地步了) 2·这个问题我还形成不了文字上的东西,不过关于having做后置定语修饰名词的分析在prep笔记上好像是有的,楼主可以翻阅一下。