题目

乳糖酶催化乳糖水解。有两项与此相关的实验，其他实验条件均设置为最适条件，实验结果如下表，以下分析正确的是 （ ） 实验一(乳糖浓度为10%)酶浓度/%01245 相对反应速率02550100200 实验二(酶浓度为2%)乳糖浓度/%05102030 相对反应速率025506565 A . 实验一增加乳糖浓度，相对反应速率将降低 B . 实验二若继续增大乳糖浓度，相对反应速率不再加大 C . 实验一如果继续增加酶浓度，相对反应速率不再加大 D . 实验二若温度升高10 ℃，相对反应速率将增大 When I entered Berkeley. I hoped to earn a scholarship. Having been a Straight-A student, I believed I could   36 tough subjects and really learn something. One such course was World Literature given by Professor Jayne. I was extremely interested in the ideas he   37  in class. When I took the first exam, I was   38  to find a 77, C-plus, on my test paper,   39  English was my best subject. I went to Professor Jayne, who listened to my arguments but remained   40 . I decided to try harder, although I didn’t know what that   41  because school had always been easy for me. I read the books more carefully, but got another 77. Again, I   42  with Professor Jayne. Again, he listened patiently but wouldn’t change his   43 . One more test before the final exam. One more   44  to improve my grade. So I redoubled my efforts and, for the first time,   45  the meaning of the word “thorough”. But my   46  did no good and everything   47  as before. The last hurdle（障碍）was the final. No matter what   48  I got, it wouldn’t cancel C-pluses. I might as well kiss the   49  goodbye. I stopped working hard. I felt I knew the course material as well as I ever would. The night before the final, I even   50  myself to a movie. The next day I decided for once I’d have   51  with a test. A week later, I was surprised to find I got an A. I hurried into Professor Jayne’s office. He   52  to be expecting me. “If I gave you the A-pluses you   53 , you wouldn’t continue to work as hard.” I stared at him,   54  that his analysis and strategy(策略) were correct. I had worked my head   55 , as I had never done before. I was speechless when my course grade arrived: A-plus. It was the only A-plus given. The next year I received my scholarship. I’ve always remembered Professor Jayne’s lesson: you alone must set your own standard of excellence. 1. A．take B．discuss C．cover D．get 2. A．sought B．presented C．exchanged D．obtained 3.. A．shocked B．worried C．scared D．anxious 4.. A．but B．so C．for D．or 5. A．unchanged B．unpleasant C．unfriendly D．unmoved 6. A．reflected B．meant C．improved D．affected 7. A．quarreled B．reasoned C．bargained D．chatted 8. A．attitude B．mind C．plan D．view 9. A．choice B．step C．chance D．measure 10.. A．memorized B．considered C．accepted D．learned 11. A．ambition B．confidence C．effort D．method 12.. A．stayed B．went C．worked D．changed 13. A．grade B．answer C．lesson D．comment 14.. A．scholarship B．course C．degree D．subject 15.. A．helped B．favored C．treated D．relaxed 16. A．fun B．luck C．problems D．tricks 17. A．happened B．proved C．pretended D．seemed 18. A．valued B．imagined C．expected D．welcomed 19.. A．remembering B．guessing C．supposing D．realizing 20.. A．out B．over C．on D．off