第19题: [单项选择]The word "they" in "…together they threaten to confuse." (Line 3, Para. 5) refers to A. engineering and the liberal-arts B. reality and noble ideals C. flexibility and a value system D. practicality and rationality 参考答案:A 答案解析:判断指代关系。文章第五段第二行、第三行的“they”都是指代前文的“engineering and the liberal-arts。”