读中国四大地理区域图，下列描述正确的一项是（ ）
磷是土壤有机质的重要组成元素，也是植物生长的营养元素。土壤水分增加有利于磷累积，气温升高和流水侵蚀会减少土壤中磷累积量。下图示意我国四川西部某山地东坡土壤中磷累积量的垂直变化。据此完成（1）~（2）题。
①提高少数民族政治、经济地位的主要手段
②保证民族自治地方享有更多自治权的措施
③协调少数民族特殊利益与国家整体利益的表现
④发展平等团结互助和谐的社会主义民族关系的重要举措
小曲在学习聚落与环境的关系时，上网查到了一副民居图片。根据民居和自然环境的关系，可以推断该民居可能位于（ ）
| A. Come in with something to say. B. Prepare general comments. C. Bring materials with you. D. Don’t make them wait. E. Have no fear. F. Go it alone. |
One of the best things you can do any time in the semester is go see the professor. So hoof on over to an office hour and have some one-on-one face time with someone who’ll help you master the material and improve your grade, to boot. But how should you have this conversation with the professor?Here are five insider tips about how to make that office hour really count:.
(1) ______ No need to get all bent out of shape about going to see the professor. The professor would actually like to see you and answer your questions. Believe it or not, he or she is on your side and is eager to see you do well. And besides, he or she has seen many students stupider than you, so nothing you’re going to ask will set the record for stupidity.
(2) ______ Even though you might feel more comfortable going with a friend or partner, the office hour will go better if it’s just you and the professor. You’ll get in more questions, the discussion will be tailored to what you need most help on, and two-party communication is almost always more productive than committee work. Your friend can wait outside for the discussion.
(3) ______ If you can’t make the official office hours, most professors are willing to make individual appointments to help you out. If you’re lucky enough to land such an accommodation, though, be sure you’re 100 percent on time. There’s nothing that ticks off a professor more than making him-or herself available for a custom office hour only to find that you don’t care enough to come on time. And besides, the professor might leave after ten minutes, which would make your trip a total loss.
(4) ______ If you’re meeting with the professor to go over a paper or test, or to ask questions about a particular lecture or reading,make sure you bring that paper or test, or your lecture notes or a copy of the article. The professor doesn’t remember the comments he or she wrote on your individual piece of work---though he or she will be able to recall them after just a brief glance at your work. And if you have your lecture notes or the article in hand, you and the professor will be able to examine specific points that are confusing to you, rather than just talking in a general way about the contents.
(5) ______ Office hours almost always go better if you bring a few specific questions to the meeting. It’s almost never good to start a meeting with general comments such as“I didn’t understand what you said about [main topic of the course]” or“I couldn’t understand any of your lectures last week.” Much better is to come in with two or three conversation-starters about a specific concept, point, or problem you didn’t understand. Keep in mind that in a fifteen-minute office hour (which is how long these things usually last), two or three questions are usually the most you’ll have time to discuss.
某研究小组将纯净的气体通入的溶液中，得到了沉淀，为探究上述溶液中何种微粒能氧化通入的，该小组突出了如下假设:
假设一：溶液中的
假设二：溶液中溶解的