请教大虾一个题

davidzxc

这是新东方逻辑讲义上的一题，答案忘记了，现在一看就头晕


no senater spoke at the convention unless he or she was a democrat. no democrat both spoke at the convention and was a senator.


which of the following conclusions can be properly drawn from the statement above?


a. no one but senators spokes at the convention.


b. no democrat spoke at the convention.


c. only democrats spoke at the convention.


d. no senater spoke at the convention.


e. some democrat senators spoke at the convention.

weiyu

我觉得选（d) s代表senator; d代表democrat; c代表convention


s+c->d->非（s+c)所以s+c不可能存在; no senater spoke at the convention.