标题: only if 引导从句 到底是条件还是结论？ [打印本页] 作者: 183077142 时间: 2011-3-27 21:43 标题: only if 引导从句 到底是条件还是结论？ 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
我在DE里面纠结 选了D 因为我觉得D的意思是 D 知道定理为真，是不可能的，只要它不能被观察证实 这里only if 引导的后面 我认为是条件 逻辑关系是 只要定理不能被证实，知道定理为真是不可能的
但是别人给出的解释是 D选项 IMPOSSIBLE KNOWN TO BE TRUE 推出 CANNOT BE PROVE BY OBSERVATION 请问大家only if 引导的是结论 还是 条件？
此题答案E 作者: sdcar2010 时间: 2011-3-27 22:02
A only if B