下午一道难题求助

这题我选了c，主要感觉后半句那个比较结构不是很清晰，不知道哪位高人能指点一下呢～多谢哦！



The recent discovery of a red oak tree sap that is anticipated to advance experimentation with natural substances in order to create cancer medicines will be able to provide chemists with a more potent mixture to work from than other trees and at a lower cost.

(A) The recent discovery of a red oak tree sap that is anticipated to advance experimentation with natural substances in order to create cancer medicines will be able to provide chemists with a more potent mixture to work from than other trees and at a lower cost

(B) The recent discovery of a red oak tree sap is anticipated to advance experimentation with natural substances in order to create cancer medicines and will be able to provide chemists with a more potent mixture to work from at a lower cost than the sap extracted from other trees

(C) The recent discovery of a red oak tree sap, which is anticipated to advance experimentation with natural substances in order to create cancer medicines, will be able to provide chemists with a more potent mixture to work from at a lower cost than other trees your answer

(D) A recently discovered red oak tree sap, which is anticipated to advance experimentation with natural substances in order to create cancer medicines, will be able to provide chemists with a more potent mixture to work from than the sap extracted from other trees can, and at a lower cost （correct）

(E) A recently discovered red oak tree sap, which is anticipated to advance experimentation with natural substances in order to create cancer medicines, will be able to provide a more potent mixture to work from than other trees and to decrease the cost

(C) The recent discovery of a red oak tree sap, which is anticipated to advance experimentation with natural substances in order to create cancer medicines, will be able to provide chemists with a more potent mixture to work from at a lower cost than other trees your answer
C错在  the recent discovery will be able to provide chemists... 但是作者想说的是a red oak tree sap will be able to...
D主语是 a red oak tree sap will be able to ....逻辑关系正确。
and at a lower cost 是省略句。the sap...will provide chemists with a more potent mixture to work from than the sap from other trees, and （will do this）at a lower cost.
另外ACE的比较也错了 The comparison "more potent mixture to work from than OTHER TREES"，明显比较双方不对。
D的比较more potent mixture to work from than the sap extracted from other trees can是正确的。
希望可以帮助你。

额，字体好小，看的眼睛都花了

这道题的考点在比较结构上

C选项The recent discovery of a red oak tree sap, which is anticipated to advance experimentation with natural substances in order to create cancer medicines, will be able to provide chemists with a more potent mixture to work from 【at a lower cost 】thanother trees your answer

LZ可以提取出句子主干，看到than后面的other trees，而句子的主语是discovery，比较对象不对等。错

而D选项A recently discovered red oak tree sap, which is anticipated to advance experimentation with natural substances in order to create cancer medicines, will be able to provide chemists with a more potent mixture to work from than the sap extracted from other trees can, and at a lower cost  

比较对象都是sap，对等。

此外，C选项【 at a lower cost 】变成了修饰动词work，逻辑上应该修饰mixture名词