题目

在克里克得出3个碱基可以排列成1个遗传密码的实验结论后，科学家们开始探索一个特定的遗传密码所对应的特定的氨基酸究竟是哪一个。尼伦伯格和马太采用蛋白质的体外合成技术，在每一个试管中加入一种氨基酸，再加入除去了DNA和mRNA的细胞提取液，以及人工合成的多聚尿嘧啶核苷酸，结果在加入了苯丙氨酸的试管中出现了多聚苯丙氨酸的肽链，如下图请回答。 (1)实验中多聚尿嘧啶核苷酸的作用是_______________________________________。 (2)细胞提取液为You will go to college some day and college is one of the most exciting stages of one’s life.If you wish to make the most of your campus(校园) experience and become a better person after those four years，then first you ought to make friends.Close friends contribute to your self­growth for they provide you with moral support that is so important to survive the stressful college life.Friends can lend a helping hand when necessary like collecting your homework when you’re too sick to leave your dorm，and help you develop the right attitude by pointing out to you your weaknesses.Being home most of your life and then suddenly finding yourself on your own in a large campus without your parents to hold your hand can be annoying.However，rather than thinking about your missing home too much，why not see this new stage in your life as an opportunity for self­growth and develop the right attitude that will prepare you for the rigors of post­graduation life，particularly when you join the workforce?Special­interest clubs or organizations are great for self­growth.Here，not only do you get the opportunity to meet with like­minded people，you can also discover more things about your field of interest.Club meetings usually include lively discussions，so go there with the right attitude.You should try to build a good name in the organization by being respectful，active and considerate to others.You might not like all of your professors，but they are there to provide knowledge you need to be successful in your chosen field.Thus，show up for each class with the right attitude and determination to learn.Whether you get along well with your professors or not has a huge effect on your self­growth as it is a measure of how well you can respect authority and obey requirements.Actively participating in a class debate(辩论) or lecture contributes to your self­growth as it helps you build confidence in speaking up and improves your communication skills.It also helps you develop the right attitude by exercising diplomacy(外交术) when you choose your words carefully especially when discussing a very politically sensitive issue and exercising patience when dealing with classmates who shoot down your ideas.【小题1】In the writer’s opinion，how can college students develop a positive attitude?A．By joining special­interest clubs.B．By focusing on their studies.C．By taking up part­time jobs.D．By making friends with others.【小题2】According to the text，college students should do many things EXCEPT ________.A．forget the familyB．be respectful at club meetingsC．try to attend each classD．take an active part in a class debate【小题3】We can learn from the text that ________.A．college life is very interestingB．friendship can help college students avoid stressC．students should choose words carefully at any occasionD．it is important to have a good teacher­student relationship【小题4】The purpose of the text is to ________.A．introduce how to show yourself in collegeB．tell college students how to socialize with othersC．give college students some advice on self­growthD．explain the importance of four­year college life