题目

下列有关实验操作、现象和解释或结论都正确的是（） 选项操作现象解释或结论 A向某无色溶液中加入足量稀盐酸酸化的Ba(NO3)2溶液出现白色沉淀溶液中一定存在B用光照射装有甲烷和氯气的混合气体气体的试管颜色逐渐变浅，试管内壁出现油状液滴甲烷与氯气发生了反应 C向蔗糖溶液中加3~5滴稀硫酸，将混合液煮沸几分钟，冷却；向冷却后的溶液中加入银氨溶液，水浴加热没有银镜产生蔗糖未发生水解 D向盛有某溶液的试管中滴加稀NaOH溶液，将湿润红文中共有10处语言错误，每句中最多有两处，每处错误仅涉及一个单词的增加、删减或修改。 增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。 删除：把多余的词用斜线（﹨）划掉。 修改：在错的词下划一横线，并在该词下面写出修改后的词。 注意：1.每处错误及其修改均限一词。 2.只允许修改10处，多者（从第11处起）不计分。 High school students sometimes feel stressed because frequent exams . Here is some suggestions on how to deal with the problem. First of all, you should have confidences and hold on to your dreams. It’s important to make a good study plan and carry them out. To stay healthy and energetic, you’d better to do some sports after school, such as playing basketball, swimming and so on. Besides, a balancing diet is helpful. You should eat more vegetables but avoid food with too much fat.  In addition, it’s a good idea to turn to your parents and teachers with help when you got into trouble . They will sure help you out.