啊，不好意思，是名词的所有格不是名词

Per mile不一定，只能知道总的，因为坐飞机的通常miles会多，总的fare也就增加。但是average不得而知。

and前后动词的时态保持一致

by 后面只能加名词或者动名词结构

十本是“L中有评论”+“出现在其他中世纪手稿”中，八本是“L中无评论”。为什么E：Electra没有伴随评论一起出现在其他中世纪手稿 是对的？只说了八本在L无评论，没说不出现在其他中世纪手稿中，也没说出现在其他中世纪手稿中时没有评论啊

in the construction "not so much X as Y", "not" isn't negating "X"—it's negating the "so much" part. these are 2 completely different constructions, with 2 different meanings.
在not so much X as Y中，not是在否定so much的程度和部分，而不是否定X，二在C中，就是在否定X本身，完全是两个结构

A为啥不对呢....

是因为 one...was their.....显然不一致

请看清楚支持/削弱的是哪一方

类比推理，山洞里的水和树里的水的区别

C中the most important不能直接做宾语，补充those更完整；them和themselves都是可以的

考的就是个comparison
首先 higher。。。than。。。固定的idiom——排除bd
其次 第一个than对比前后要一致
this year‘s than last’s 平行 this year than last 平行
所以排出ec
选a

我找的很简单
首先画线最后应该是个平行结构，倒着看
a）and how 前面找不到平行的结构 不对
c）either and 搭配错误
d）of the job和of how 不平行
第二部对比b e
leaves和leave 区别 主语是absence辣么去掉b 选e

我到现在都不明白 that 和 to do到底啥时候怎么用。。。

note that you have "compared to motor vehicles...", which implies that we are making a direct comparison between pollutants and motor vehicles (rather than between pollutants and pollutants, as in the correct answer. that's nonparallel and thus wrong.

"that" stands for" the total amount of pollutant "

the real problem is that "is" has no parallel in the first part of the comparison - i.e., the first part doesn't say "is emitted" or "are emitted" - and so the comparison is wrong.

twice more than 比...多两倍（三倍）
twice as much as 是...的两倍

If I use "with" to introduce a noun modifier I do not use a comma before it so that it is "touching" the noun it modifies; if I use "with" as an adverbial modifier I do use a comma before it.

in the construction "x of y, which", the referent could be either "x" or "y" depending on the surrounding context.