题目

红细胞含有大量血红蛋白，红细胞的机能主要是由血红蛋白完成，血红蛋白的主要功能是携带O2和CO2 ， 我们可以选用猪、牛、羊或其他脊椎动物的血液进行实验，来提取和分离血红蛋白．请回答下列有关问题： （1） 血红蛋白的提取和分离一般可分为四步：、粗分离、和． （2） 实验前取新鲜的血液，要切记在采血容器中预先加入柠檬酸钠，取血回来，马上进行离心，收集血红蛋白溶液． ①加入柠檬酸钠的目的是．②以上所述的过程即 阅读下列应用文及相关信息，并按照要求匹配信息。请在答题卡上将对应题号的相应选项字母涂黑。 以下是为留英学生编写的系列留学指南的简介： A. The number—one guide to what to study in the UK This two-volume Guide features up-to-date and in-depth information about UK course options and institutions. It also includes course charts, teaching and research ratings, and advice on choosing your course. B. The A to Z of where to study in the UK A reference directory of UK institutions belonging to the British Council’s Education Counselling Service. Includes easy-to-use comparative data on everything from accommodation to courses and fees. C. The essential online guide to UK education This site gives you instant access to a wide range of information on studying and living in the UK, including hotlinks to the British Council’s Virtual Campus and institutions’ own web sites. D. The practical guide to making the most of your UK experience This fully updated book features the latest information about study opportunities, traveling to the UK, arranging accommodation, working in the UK, financial and legal matters, and student life. E. New guide to choosing the right UK course Every year, The Times newspaper compiles a league table of all the UK's ninety-seven universities. This is published as The Good University Guide, which features over fifty tables ranking universities by degree subject. F. The magazine that shows why so many international students choose to study in the UK If you’ve enjoyed reading this magazine and want to keep up with the latest UK student news and views, place your order now for issues 3 and 4. 以下是留英指南图书或杂志的封面，请匹配封面与其对应的简介： 1. 2. 3. 4. 5.