[SC悬赏令] OG17 求教三题比较+省略

今天刷OG17，新的版本，做到后面错的简直没脸见人.....
其中有三题关于比较+省略结构的题，CD转了一圈，MANHATTEN转了一圈，还是懂不了，摔！！！好生气，可还是要保持微笑。
这三题是这样的。虽然在新版上，但都不是新题，但OG13千行上也没有就是了。


758. Prices at the producer level are only 1.3 percent higher now 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 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  

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  

772. Heating-oil prices are expected to be higher this year than last because refiners are paying about $5 a barrel more for crude oil than they were last year.

(B) Heating-oil prices are expected to rise higher this year over last because refiners pay about $5 a barrel for crude oil more than they did

(C) Expectations are for heating-oil prices to be higher this year than last years’ because refiners are paying about $5 a barrel for crude oil more than they did

(D) It is the expectation that heating-oil prices will be higher for this year over last because refiners are paying about $5 a barrel more for crude oil now than what they were

(E) It is expected that heating-oil prices will rise higher this year than last yea’s because refiners pay about $5 a barrel for crude oil more than they did

777. According to recent studies comparing the nutritional value of meat from wild animals and meat from domesticated animals, wild animals have less total fat than livestock fed on grain and more of a kind of fat thought to be good for cardiac health.

A wild animals have less total fat than do livestock fed on grain and more of a kind of fat they think is  

C wild animals have less total fat than that of livestock fed on grain and have more fat of a kind thought to be  

D total fat of wild animals is less than livestock fed on grain and they have more fat of a kind thought to be  

E total fat is less in wild animals than that of livestock fed on grain and more of their fat is of a kind they think is

之前有人在CD上讨论过前两题的比较，但不是我纠结的点。

第一句和第二句这么像，为什么第一句是those of a year ago，而第二句是this year，不都是前后的价格在比较吗?而且OG解释上也说了上下两题都是价格的比较，那说明就是省略的问题啦？可在什么情况下能省略，什么情况下不能？

第三题更郁闷，为什么是wild animal和livestock相比，而不是它俩的fat相比，我选了选项里有less...than that of livestock的选项，错的就是，但答案里还是说是两者的fat在比较（the sentence reports research findings on the comparison between the fat content of wild animals and that of domestic livestock）尼玛答案里都说that of domestic livestock啊！！！为什么这个选项不对？

另外第三题答案的解释里有一句话（Note that while the phrase "less total fat than livestock" differs from the phrase "less total fat than do livestock" in the orginal, either would be correct here.）他不解释还好，解释了我疑问更多了，为什么这里有个do，这个do还是在livestock前面的？不应该是less total fat than livestock do have 吗？可这样好像又不平行，应该不能这样写吧，跪求各位NN出山给我解答一题可好~~~~~