IF和WHETHER

在引导从句时，假如其他情况都相同，能否仅按WHETHER优于IF来选呢？偶认为在现在的实战中，以前的一些原则，即使是ETS的原则，也不能作为判断的依据。

Art historians are using a process known as infrared scanning in analyzing the Mona Lisa to determine if it has been altered since completion and if Leonardo da Vinci first sketched the figure in black, as done by many artists of the time.

(A) if it has been altered since completion and if Leonardo da Vinci first sketched the figure in black, as done

(B) if it had been altered since completion and if Leonardo da Vinci first sketched the figure in black, a practice employed

(C) whether it has been altered since completion and whether Leonardo da Vinci first sketched the figure in black, a practice employed

(D) whether it was altered since completion and whether Leonardo da Vinci first sketched the figure in black, as was done（C）

(E) whether it had been altered since completion and whether Leonardo da Vinci first sketched the figure in black, a practice done

在上述例句中，答案C的第二个WHETHER是不是应该改成被动形式以和前面平行呢？

ETS的考点：whether 引导名词性从句；if 引导状语从句。

主动优于被动－简洁

用被动－一般由于动作的实施者不明确。

所以，即使上面的C要改的话，偶觉得也是把第一句改成主动和后面的平行更好。