Nevertheless, something could still be done.
但是这并不是徒劳，
Suppose that at some point in the process of running through all the rotor positions, the set-up happens to be:
假设在运行过程中的某一点，机器的状态变成这样：
Then it may be asked whether the letters GFGCORL could, or could not, be obtained from GENERAL by the effect of a plugboard swapping.
然后我们可以考察，GNGCORL是否有可能通过配线板而编码成GENERAL。
In this example, the answer is 'no', since no swapping could leave the first G unchanged, but swap the second G into an N;
在这个例子中，显然是不行的，因为没有一种对换，可以使第一个G保持不变，而第二个G变成N，
no swapping could turn the first E of GENERAL into an F and the second into a C.
也没有一种对换，可以把第一个E变为F，却把第二个E变成C。
Furthermore, no swapping could change the R of GENERAL into an O, but then change the A into an R.
当然，也没有一种对换，可以把R变成O，但却把A变成R。
Any one of these observations suffices to rule out that particular rotor position.
总之，以上任何一项观察，都可以排除掉这种盘位。
One way of thinking of this question is in terms of consistency.
这个问题的一个思路，就是相容性。
Having fed the cipher-text into the Enigmas, is the output consistent with the known plain-text, in that it differs only by virtue of swapping?
把密文输入谜机，输出是否与明文只差一组对换？
From this point of view, the correspondences (OR) and (RA), or (EF) and (EC), are contradictions.
从这一点看，上例中的（OR）和（RA），或（EF）和（EC），就会引起矛盾。
A single contradiction is enough to eliminate all the billions of possible plugboards, on this hypothetical machine.
只要有一个矛盾，就可以排除几十亿种配线关系。