X-ray examination of a recently discovered painting---judged by some authorities to be a self-portrait by Vincent van Gogh---revealed an underimage of a woman's face. Either van Gogh or another painter covered the first painting with the portrait now seen on the surface of the canvas. Because the face of the woman in the underimage also appears on canvases van Gogh is known to have painted, the surface painting must be an authentic self-portrait by van Gogh.
The conclusion is properly drawn if which of the following is assumed?
A. If a canvas already bears a painted image produced by an artist, a second artist who uses the canvas to produce a new painting tends to be influenced by the style of the first artist.
B. Many painted canvases that can be reliably attributed to van Gogh contain underimages of subjects that appear on at least one other canvas that van Gogh is known to have painted.
C. Any painted canvas incorrectly attributed to van Gogh would not contain an underimage of a subject that appears in authentic paintings by that artist.
D. A painted canvas cannot be reliably attributed to an artist unless the authenticity of any underimage that painting might contain can be reliably attributed to the artist.
E. A painted canvas cannot be reliably attributed to a particular artist unless a reliable x-ray examination of the painting is performed.
逆否命题等价于原命题。
如果C成立，那么意味着C的逆否命题也成立，即：如果一幅作品contain an underimage of a subject that appears in authentic paintings by van Gogh，那么这幅作品一定是van Gogh的真迹。而这正是原文表达的内容。
B……看到many就能判断这是个错误选项了吧，毕竟many不代表all。何况即使是all，也即：所有梵高的作品都含有underimages blahblah，也不代表含有这些underimage的作品一定是梵高画的啊。作者: 江米糕 时间: 2015-11-11 10:13:36
岳然 发表于 2015-11-10 02:29
逆否命题等价于原命题。
如果C成立，那么意味着C的逆否命题也成立，即：如果一幅作品contain an underimag ...
