OG 13 SC 107 求助

skm

107.While it costs about the same to run nuclear plants as other types of power plants, it is the fixed costs that stem from building nuclear plants that makes it more expensive for them to generate electricity.
(A) While it costs about the same to run nuclear plants as other types of power plants, it is the fixed costs that stem from building nuclear plants that makes it more expensive for them to generate electricity.
(B) While the cost of running nuclear plants is about the same as for other types of power plants, the fixed costs that stem from building nuclear plants make the electricity they generate more expensive.
(C) Even though it costs about the same to run nuclear plants as for other types of power plants, it is the fixed costs that stem from building nuclear plants that makes the electricity they generate more expensive.
(D) It costs about the same to run nuclear plants as for other types of power plants, whereas the electricity they generate is more expensive, stemming from the fixed costs of building nuclear plants.
(E) The cost of running nuclear plants is about the same as other types of power plants, but the electricity they generate is made more expensive because of the fixed costs stemming from building nuclear plants.

答案B：the same as后面省略了the cost。
请问：在比较的时候，什么时候可以省略，什么时候要用代词（that,those）指代？

叮叮当612

帮顶，，，，
另，B的逗号以后the fixed costs和前半句话是怎样的关系？