LSAT10-4-4:一个很低级得问题

rabbitbug

4.    Only if the electorate is moral and intelligent will a democracy function well.
Which one of the following can be logically inferred from the claim above?
(A) If the electorate is moral and intelligent, then a democracy will function well.
(B) Either a democracy does not function well or else the electorate is not moral or not intelligent.
(C) If the electorate is not moral or not intelligent, then a democracy will not function well.
(D) If a democracy does not function well, then the electorate is not moral or not intelligent.
(E) It cannot, at the same time, be true that the electorate is moral and intelligent and that a democracy will not function well.
答案C, 请问D在这里为什么就不能用了? 是不是因为only if 和if only得区别, 他们两个得区别在哪里呢? 还请大家不吝赐教!

snow_mountain

only if 表示的是necessary。 故， function well --> moral and intelligent.  逆否就是C啦。

D 是否命题。

if only 我的理解是sufficient.

八戒

同意楼上

rabbitbug

Thanks a lot for the 2 NN's reply. I remember the point.