题目

研究性学习小组进行溴乙烷的制备及性质探究实验．探究一：该小组制备溴乙烷的步骤如下：①向装置图所示的U形管和大烧杯中加入冷水；②在小烧杯中按照一定比例配制乙醇、水、浓硫酸的混合液；③向装置图所示的圆底烧瓶中加入一定量研细的溴化钠和少量碎瓷片；④将冷却至室温的混合液转移到圆底烧瓶中，加热；⑥制取溴乙烷．同答下列问题： （1） 步骤②向乙醇和水中缓缓加入浓硫酸时，小烧杯要置于冷水中冷却，除了避免硫酸小液第二节完形填空（共20小题；每小题1分，满分20分）In a hall, a lecturer was giving a lecture to his students on stress management. At the beginning of the speech,he 41 a glass of water and asked the audience, “How 42 do you think this glass of water is?” The students’ answers 43 from 20g to 500g. “Actually,it does not matter on the absolute 44 . But it depends on how 45 you hold it. If I hold it for a minute, it is OK. If I hold it for a(n) 46 , I will have an ache in my right arm. If I hold it for a day, you will have to 47  an ambulance. It is exactly the 48 weight, but the longer I hold it, the 49 it becomes.” Hearing these words,the whole audience became silent, lost in thought. After a moment, the lecturer continued, “ 50 we carry our burden all the time, 51 , we will not be able to carry on with the burden becoming increasingly heavier,  52 heavy for us to bear. “So, what you have to do is to 53 the glass, rest for a while 54 holding it up again.” As is shown in the story above, we have to put down the burden periodically, 55 we can be refreshed and are able to carry on. So before you 56 home from work tonight, put the burden of 57 down. Don’t carry it back 58 . You can pick it up tomorrow. Whatever burden you are having now on your 59 , let it down for a moment if you can. Life is short,  60 it!  41. A. supported            B. drank                C. needed                        D. raised 42. A. heavy                 B. pure           C. sweet                       D. many 43. A. differed             B. ranged              C. numbered                 D. limited 44. A. weight            B. volume             C. height                     D. quantity45. A. tight                B. long                  C. difficult                   D. high 46. A. day                  B. second              C. hour                D. half 47. A. require                  B. invite          C. call                D. ask 48. A. proper                  B. same           C. right                   D. usual 49. A. less                  B. lighter              C. more                   D. heavier 50. A. If                     B. Unless         C. While                   D. Since 51. A. now and then    B. little by little        C. sooner or later      D. sometimes 52. A. too              B. so              C. rather                D. quite53. A. put away       B. put down          C. put aside            D. put back 54. A. after            B. for              C. by                       D. before 55. A. so that                B. even if            C. as if                D. as soon as56. A. leave                  B. clean                C. approach                  D. return 57. A. life                  B. duty                      C. task                     D. work 58. A. home                  B. office             C. company             D. family 59. A. shoulders            B. heart              C. body                   D. hands 60. A. do                   B. like                C. love                D. enjoy