题目

阅读理解 A new study shows students who write notesby hand during lectures perform better on exams than those who use laptops. Students are increasingly using laptopsfor note-taking because of speed and legibility(清晰度).But the research has found laptop usersare less able to remember and apply the concepts they have been taught. Researchers performed experiments that aimedto find out whether using a laptop increased the tendency to make notes mindlesslyby taking down word for word what the professors said In the first experiment, students were giveneither a laptop or pen and paper .Th5．逻辑推理是化学学习中常用的思维方法，下列推理正确的是（　　）A．化合物是由不同元素组成的纯净物，所以由不同种元素组成的纯净物一定是化合物B．中和反应生成盐和水，则生成盐和水的反应一定是中和反应C．单质中只含有一种元素，所以只含有一种元素的物质一定是单质D．活泼金属能与稀盐酸反应放出气体，则能与稀盐酸反应放出气体的物质一定是活泼金属