请教XDF SECTION 1 中的 2 题

请教XDF SECTION 1

7, Even today, a century after pasteaur developed the first vaccine, rabies almost always kills its victims unless inoculated in the earliest stages of the disease.

(a) its victims unless inoculated

(b) its victims unless they are inoculated

(c) its victims unless inoculation is done

(d) the victims unless there is an inoculation

(e) the victims unless inoculated

Answer (B) why not c?

10, Climatic shifts are so gradual as to be indistinguishable at first from ordinary fluctuation in the weather.

(a) so gradual as to be indistinguishable

(b) so gradual they can be indistinguishable

(c) so gradual that they are unable to be distinguished

(d)gradual enough not to be distinguishable

(e) gradual enough so that one cannot ditinguish them

Answer (a) why not c?

where can find answer explaination of xdf sc? thanks lot.

请DX指点！

自己顶！！！

1.动词由于抽象名词

2.be unable to be done/ be able to be done这样的表述在GMAT中是错误的

我知道这样说很没说服力`` 等高手来 

新东方的书没有讨论``` 可以从大全里找到对应的题目再来论坛找