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
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
-- by 会员 清月依云 (2012/11/15 14:07:50)
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
-- by 会员 MiaZhang (2012/11/15 17:53:14)
