[求助]非常困惑的比较及省略的问题

sillytortoise

之前在曼哈顿的论坛上ron大概说过比较的话省略部分的时态自动被认为是前面的时态，当时态改变的话，必需要将主谓补出，比如：
i can run as fast now as in high school --> incorrect, since i'm not in high school anymore.
i can run as fast now as i could in high school --> correct, with the necessary tense change.

Prices at the producer level are only 1.3 percent higher now than a year ago and are going down, even though floods in the Midwest and drought in the South are hurting crops and therefore raised corn and soybean prices.
(A) than a year ago and are going down, even though floods in the Midwest and drought in the South are hurting crops and therefore raised
(B) than those of a year ago and are going down, even though floods in the Midwest and drought in the South are hurting crops and therefore raising
(C) than a year ago and are going down, despite floods in the Midwest and drought in the South, and are hurting crops and therefore raising
(D) as those of a year ago and are going down, even though floods in the Midwest and drought in the South hurt crops and therefore raise
(E) as they were a year ago and are going down, despite floods in the Midwest and drought in the South, and are hurting crops and therefore raising
正确答案是B
Ron在论坛上说不论是than a year ago还是 than those of a year ago都是可以的，在这里我想请教的是为什么明明时态改变了却不需要补出主谓呢，包括在egmat上的帖子这样说
I agree with my colleague Ron Purewal (cited above) that the comparisons in A and C aren't necessarily faulty. There are other reasons to eliminate those choices.
I can't say something like this:

American crows are larger today than in ancient China.

If we filled in "those," this might make sense: "American crows are larger today than those (crows) in ancient China." However, the actual implied meaning here is a comparison between two modifiers: "today" and "in ancient China." "American crows are larger today than (they were) in ancient China." This would make it seem that American crows existed in ancient China!
差别在哪呢，按照时态来说我觉得prices were是不能省的啊~~求大牛回复，感激不尽

ReggieYANG

同样也有疑问，补充下
ron在2011-05-12中有个例子
Company's earnings in the first quarter were more than double those of the previous quarter.
他说这里必须加上those of不然就是 earnings vs time period
感觉跟这个有点像

andrealuo

ReggieYANG 发表于 2016-10-6 22:10
同样也有疑问，补充下
ron在2011-05-12中有个例子
Company's earnings in the first quarter were more tha ...

我感觉不一样，似乎是两个概念。
你给出的例子是由于前句有多个可以指代的所以不清晰，但是本题是没有这个混淆的
这里有没有those of 确实都可以，有了those of稍显累赘了，但是考虑到后句的主语不对所以排除ACE
在BD之间选，D的现在时有点不科学

sillytortoise

ReggieYANG 发表于 2016-10-6 22:10
同样也有疑问，补充下
ron在2011-05-12中有个例子
Company's earnings in the first quarter were more tha ...

这题其实必需加上those of的原因是因为the previous quater前面缺少介词，并且这个地方应该不存在我说的这个问题。
首先，如果是比较句子的主语的话，补充完全句也就是
Company's earnings in the first quarter were more than double the company’s earnings in the previous quarter.
如果是比较的是状语的话，补充完全句是
Company's earnings in the first quarter were more than double the company's earnings in the previous quarter were.
发现没有两边都是were所以是不存在时态不对等而问题的，根本问题是缺介词，比较的本质是不要造成歧义，其他时候包括RON给出的原则其实也是很灵活的，只能再选项中挑最好的，不能想好选项对着去挑，我之前提的这个问题其实是因为本身这个句子不会造成歧义，而且一定是指过去所以才省掉了，我后面才想起来

VincentFSJ

我觉得是than 加those和加时间不要介词都是可以的，不带介词的时间可以通指那个时间的状态吧，比如og的than last 比如than before包括than expected，当然我是不完全归纳总结哈

ReggieYANG

sillytortoise 发表于 2016-10-7 21:24
这题其实必需加上those of的原因是因为the previous quater前面缺少介词，并且这个地方应该不存在我说的 ...

谢谢
贴一个

关于比较的省略（来自elory的语法整理）：

对主谓宾全的句型
主语比较：  A do sth than B do.（AB为对等名词，加do是为了显示这是一个可以发出动作的名词，因而确定是主语，进而确定是主语对比）

介宾比较：  A do sth of C1 by D1 than of C2 by D2.（C1C2，D1D2对等名词）

宾语比较：  A do C1 than C2.(C1C2为对等名词）

状语比较：  A do sth than usual/ever /before/people expected(直接加状语）

GMAC就这几下子，原则就是清楚地指示什么跟什么比。
按照这个原理，对下一种句型只有主谓，没有宾语的句子，因为没有宾语，只可能有主语比较，因而不需要重复do来确认这是一个可发出动作的主语，所以其比较形式如下：

I eat faster than you.注意与下句区别 ，此时不需要补出do
I eat apple faster than you do 有宾语时补出do清晰；
其实不补do也可以，因为根据逻辑I 不会吃you ,只能是吃apple ,有任何疑问参阅曼哈顿比较章节；