问题。GWD里关于to be able和the ability

mlvince

The coyote is one of several recent ecological success stories: along with the white-tailed deer, the moose, and other species that are enlarging their natural domains, they have established themselves as supreme adapters in an era when the capability to adjust to the environmental changes wrought by human beings has created a whole new class of dominant large mammals.
A.    they have established themselves as supreme adapters in an era when the capability
B.    they have established themselves as being supreme adapters in an era when being able
C.    it has established itself as a supreme adapter in an era when to be able
D.    it has established itself as being a supreme adapter in an era when its ability      
E.    it has established itself as a supreme adapter in an era when the ability

答案是e，c这里to be able为什么不如he ability？？我一直认为to be able是优选的－－谢谢

mlvince

Gail小M

C:when to be able to adjust to the environmental changes wrought by human beings HAS CREATED a whole new class of dominant large mammals.

E:when the ABILITY to adjust to the environmental changes wrought by human beings HAS CREATED a whole new class of dominant large mammals.

For C, there is no subject of the sentence, what has created a whole new class？..

mlvince

thx!.我大意了，题目都没看完