标题: OG 12 SC 81 有关平行的问题 [打印本页] 作者: happydanni 时间: 2011-8-10 11:28 标题: OG 12 SC 81 有关平行的问题 81. Recently physicians have determined that stomach ulcers are not caused by stress, alcohol, or rich foods, but a bacterium that dwells in the mucous lining of the stomach. (A) not caused by stress, alcohol, or rich foods, but (B) not caused by stress, alcohol, or rich foods, but are by (C) caused not by stress, alcohol, or rich foods, but by (D) caused not by stress, alcohol, and rich foods, but (E) caused not by stress, alcohol, and rich foods, but are by