题目

萌发的大麦种子中存在着两种淀粉酶：α﹣淀粉酶和β﹣淀粉酶．α﹣淀粉酶耐热不耐酸；β﹣淀粉酶酎酸不耐热，70℃处理15min即变性失活．为测定萌发种子中α﹣淀粉酶和β﹣淀粉酶活性的差异，将发芽3天的大麦种子加蒸馏水研磨匀浆、离心取上清液得到淀粉酶提取液，进行如下实验． 操作步骤1号试管2号试管3号试管①加淀粉酶提取液1mL1mL1mL②预处理70℃恒温水浴15min，取出冰浴中冷却高温使α﹣淀粉酶和β﹣淀粉酶失活不处理③加缓冲液2mL2mL2mL④预保 完形填空。        While I was waiting to enter university, I saw in a newspaper a teaching job wanted at a school about ten miles from where I___1___. Being very short of money and wanting to___2___ something useful I applied (申请). Fearing as I did so, that without a degree and with no ___3___ of teaching my chances of getting the job were ___4___ However, three days later, a letter ___5___, calling me to Croydon for a___6___with the headmaster. It proved to be a___7___journey: a train to Croydon station, a ten-minute bus ride and then a walk of at ___8___ a quarter of a mile. As a result I arrived there, feeling___9___hot to be nervous. It was clearly the ___10___ himself that opened the door. He was___11___and round.     “The school,” he said, “is made up of one___12___of twenty-four boys between seven and thirteen.” I should have to___13___all the subjects except art, which he taught himself. I should have to___14___the class into three groups and teach them in turn at three different___15___, and I was disappointed at the thought of teaching maths-a___16___at which I wasn’t very good at school. Worse perhaps was the idea of___17___to teach them on Saturday afternoon because most of my friends would be___18___themselves at that time. Before I had time to ask about my salary (薪水), he got up to his___19___. “Now,” he said, “you’d better meet my  wife. She is the one who really       20     this school.” (     )1. A. lived  (     )2. A. buy    (     )3. A. hooks  (     )4. A. great  (     )5. A. arrived(     )6. A. match  (     )7. A. comfortable(     )8. A. first  (     )9. A. almost  (     )10.A. headmaster  (     )11.A. bad    (     )12.A. class  (     )13.A. like    (     )14.A. connect  (     )15.A. classes  (     )16.A. book    (     )17.A. forcing  (     )18.A. enjoying  (     )19.A. feet    (     )20.A. likes   B. played  B. do      B. experienceB. helpfulB. received  B. meeting  B. difficultB. last    B. so      B. student  B. glad    B. dozen  B. practise  B. divide  B. levels  B. lesson  B. forgettingB. helping  B. hands  B. lives in   C. studiedC. teachC. materialC. niceC. returnedC. quarrelC. pleasantC. leastC. too  C. teacherC. shortC. groupC. study C. joinC. placesC. problemC. havingC. studyingC. letterC. runs D. worked          D. write           D. means           D. tight           D. written         D. sight-seeing    D. short           D. most           D. very            D. wife            D. smiling         D. score           D. teach           D. tear            D. subjects        D. subject         D. managing        D. watching        D. wife            D. starts