题目

如图是小梅配制50g溶质质量分数为12%的NaCl溶液的实验操作示意图： （1）指出图中的一处错误操作 ． （2）配制时应选择容量为 mL（10mL或50mL或100mL）的量筒量取所需要的水． （3）用上述图示的序号表示配制溶液的操作正确顺序为 ． 答案：考点】一定溶质质量分数的溶液的配制． 【专题】溶液、浊液与溶解度． 【分析】（1）根据天平的正确使用方法进行分析； （2）根据量筒的正确使用方法进行分析； （3）根据正确配置溶液的比值是计算、称量、溶解、装瓶进行分析． 【解答】解：（1）天平称量药品质量时，不能将药品直接放在托阅读理解。     My students often tell me that they don't have "enough time" to do all their schoolwork.      My reply is often a brief "You have as much time as the president." I usually carry on a bit about there being twenty-four hours in the day for everyone, and suggest that"not enough time" is not an acceptable explanation of not getting something done.      Once in graduate school, I tried to prove to one of my professors by saying that I was working hard. His answer to me was,"That's irrelevant (无关的). What's important is the quality of your work." Since thenI have had time to think carefully about the "hard worker" dodge (诀窍), and I have come to some conclusions- all relevant to the problem of how much time we have.      If you analyze the matter, you can identify two parts of the problem: There is, of course, the matter of "time", which we can think of as fixed. Then there is the problem of "work" during that time. But, as myprofessor suggested, it's not how hard one works but the quality of the product that's important.      That led me to a new idea: the quality of the work. That concept is perhaps best explained by a sign I oncesaw on the wall in someone's office: "Don't work harder. Work smarter." There is a lot of sense in that idea.      If you can't get more time, and few of us can, the only solution is to improve the quality of the work. Thatmeans thinking of ways to get more out of the same time than we might otherwise get. That should lead us toan analysis of our work habits. Since"work" for students usually means "homework", the expression "workhabits" should be read as"study habits".      Then, as a smart student, you will seek to improve those skills that you use in study, chiefly reading andwriting. If you learn to read better and write better, there are big benefits that pay off in all your studies. 1. From the passage, we know that the author is probably ______. A. a poet B. an educatorC. a novelist D. an engineer2. We can infer from the 2nd paragraph that we students still _____.A. have enough time B. can meet the president C. get everything done well D. should accept the explanation  3. Which of the following is TRUE according to the passage?A. The author's students make good use of their time to do all their homework. B. The author tried to tell the professor that he/she (author) had done a good job. C. You can't improve the quality of the work if you can't get more time. D. You'll try to improve your skills in reading and writing if you're a clever student. 4. What's the passage mainly about? A. Students don't have enough time. B. Don't work harder; work smarter. C. No one can get more time. D. Read better and write better.