第27题: [单项选择]有利于操作的是()。 A. 急冷油塔顶温尽可能偏低 B. 汽油干点偏高 C. 裂解轻质油进入重质汽油中 D. 油水密度相差大,分离效果好 参考答案:D
第28题: [单项选择]Passage Three Questions 32 to 35 are based on the passage you have just heard. A. 0.7 percent. B. 0.9 percent. C. 20 percent. D. 80 percent. 参考答案:B 答案解析:[听力原文] What percentage of American GDP was occupied by agriculture