41. Under a provision of the Constitution that was never applied. Congress has been required to call a conven­tion for considering possible amendments to the document when formally asked to do it by the legisla­tures of two-thirds of the states. 
A. was never applied, Congress has been required to call a convention for considering possible amendments to the document when formally asked to do it
B. was never applied, there has been a requirement that Congress call a convention for consider­ation of possible amendments to the document when asked to do it formally
C. was never applied, whereby Congress is required to call a convention for considering possible amendments to the document when asked to do it formally
D. has never been applied, whereby Congress is required to call a convention to consider possible amendments to the document when formally asked to do so
E. has never been applied. Congress is required to call a convention to consider possible amend­ments to the document when formally asked to do so
 
1. 句子的完整性(一级排除C，D )
Whereby 是个从属连词, 句子结构： 加上连词 whereby 造成没有主句
By introducing the subordinating conjunction whereby, C and D produce sentence fragments. è无主句

2. 时态 ： 现在时 和 过去时 不能统一(二级排除A,B )

3. 表示目的用不定式 call … to do 比 call .. for doing 要好

4. 代词： 指代动作的时候 用 do so , 不用 do it.
uses of a pronoun (it) with no noun referent.

5. There has been 不好