问个逻辑题，新东方兰皮上的

yuanzi15

6. Damaged nerves in the spinal cord do not regenerate themselves naturally, nor even under the spur of nerve-growth stimulants. The reason, recently discovered, is the presence of nerve-growth inhibitors in the spinal cord. Antibodies that deactivate those inhibitors have now been developed. Clearly, then, nerve repair will be a standard medical procedure in the foreseeable future.
Which of the following, if true, casts the most serious doubt on the accuracy of the prediction above?
(A) Prevention of the regeneration of damaged nerves is merely a by-product of the main function in the human body of the substances inhibiting nerve growth.
(B) Certain nerve-growth stimulants have similar chemical structures to those of the antibodies against nerve-growth inhibitors.
(C) Nerves in the brain are similar to nerves in the spinal cord in their inability to regenerate themselves naturally.
(D) Researchers have been able to stimulate the growth of nerves not located in the spinal cord by using only nerve-growth stimulants.
(E) Deactivating the substances inhibiting nerve growth for an extended period would require a steady supply of antibodies.

答案选A

xma48215

因为是By-product，所以每次secreat的量都不一样~因此就不可能standarization。我是这样理解的~

yuanzi15

表示质疑，有别的解释么？

nini571

前提:inhibitors存在>神经不能再生

结论:降低inhibitors的抗体发明>神经修复成为a standard medical procedure

直接推翻前提,即神经不能修复只是大脑功能inhibiting nerve growth的副产品而已,是连带作用而不是因果关系.前提不成立,结论也无法推出.