求教各位ＮＮ！

Ricky2835

No mathematical proposition can be proven true by observation. It follows that it is impossible to know any mathematical proposition to be true.


The conclusion follows logically if which one of the following is assumed?


(A) Only propositions that can be proven true can be known to be true


(B) Observation alone cannot be used to prove the truth of any proposition


(C) If a proposition can be proven true by observation then it can be known to be true.


(D) Knowing a proposition to be true is impossible only if it cannot be proved true by observation


(E) Knowing a proposition to be true requires proving it true by observation
此题为何D不能选　D的意思是说如果proposition不能被observation证明是正确的 那么Knowing a proposition to be true is impossible  这和原文的内容是一致的 而E只是对原文逆否了一下 就变正确答案了