问题 计算题

为了测定某铜锌合金中锌的质量分数,某同学利用一定量的该合金与稀硫酸反应,进行了三次实验,相关的实验数据记录如下表。

(1)计算该铜锌合金中锌的质量分数。

(2)计算所用稀硫酸中溶质的质量分数。(结果精确到0.1%)

(可能用到的相对原子质量H―1 O―16 S―32 Cu-64 Zn―65)

答案

(1)×100%=70%

(2)50g稀硫酸与10g该合金反应时,有6.5g锌参加反应,锌有剩余,而硫酸完全反应。设50g稀硫酸中硫酸的质量为x。

         Zn+H2SO4==ZnSO4+H2↑ 

         65     98      

        6.5g    x 

        

        x=9.8 g   

       

答:该铜锌合金中锌的质量分数为70% ;稀硫酸中硫酸的质量分数为19.6% 。

完形填空

It often appears that we have more to gain by speaking than by listening. One big advantage of speaking is that it gives you a chance to control others’ thoughts and actions. Whatever your goal is — to have a boss hire you, to   36  others to vote for the person of your  37  or to describe the  38   you want your hair cut ... the key to success seems to be the  39  to speak well.

Another  40  advantage of speaking is the chance it provides to  41   the admiration, respect, or liking of others. Tell jokes, and everyone will think you’re really a  42   man. Tell them all you know, and they’ll be  43  by your wisdom. But keep quiet, and it seems as if you are a  44  person.

Finally, talking gives you the  45  to release (释放) energy in a way that listening can’t. When you’re   46  , the chance to talk about your problems can often help you feel better. In the same way, you can often   47   your anger by letting it out orally. It is also helpful to   48   your excitement with others by talking about it,  49   keeping it inside often leaves you feeling as if you might burst.

While it is true that talking does have many advantages, it’s important to  50   that listening can do good to listeners, too. As you’ll soon read, being a good listener is one good way to  51  others with their problems; and what better way is there to have others   52  you? As for controlling others, it may be true that it’s hard to be persuasive while you’re listening, but your  53  to hear others out will often make them open to your ideas   54  . Listening is often reciprocal (互惠的). “You get what you  55  .”

36. A. insist           B. advise    C. persuade             D. suggest

37. A. friend      B. relation      C. choice         D. leader

38. A. idea            B. way       C. means         D. plan

39. A. resource      B. energy          C. power          D. ability

40. A. obvious       B. easy       C. new            D. special

41. A. gain            B. grasp     C. remain         D. seize

42. A. successful    B. simple     C. wise         D. stupid

43. A. affected    B. impressed   C. instructed     D. moved

44. A. fruitless          B. priceless     C. worthless    D. senseless

45. A. pleasure          B. course      C. duty        D. chance

46. A. in trouble     B. in danger   C. in debt       D. in silence

47. A. reduce       B. lengthen     C. deepen        D. widen

48. A. control       B. share      C. enjoy         D. remove

49. A. or               B. so              C. for               D. though

50. A. suppose          B. notice     C. realize     D. imagine

51. A. fail         B. cure       C. hurt        D. help

52. A. appreciate  B. listen to    C. envy      D. support

53. A. kindness   B. favor    C. willingness  D. eagerness

54. A. by turns              B. in return   C. in turn     D. in order

55. A. lose         B. ask for          C. need        D. give

单项选择题 A1/A2型题