晶体二极管的正向偏置是指()。A、阳级接高电位,阴极接低电位 B、阳级接低电位,阴极接

题型:单项选择题

问题:

晶体二极管的正向偏置是指()。

A、阳级接高电位,阴极接低电位

B、阳级接低电位,阴极接高电位

C、二极管没有阳阴极之分

D、二极管极性任意接

考点:维修电工考试维修电工(初级)维修电工(初级)题库
题型:单项选择题

(14分)过氧化氢H2O2,(氧的化合价为-1价),俗名双氧水,医疗上利用它有杀菌消毒作用来清洗伤口。对于下列A~F涉及H2O2的反应,回答相关问题:

A.Na2O2 +2HCl= 2NaCl+H2O2   

B.Ag2O+ H2O2=2Ag+O2↑+ H2O

C.2 H2O2="2" H2O+O2

D.3 H2O2+Cr2(SO4)3+10KOH=2K2CrO4+3K2SO4+8 H2O

E.H2O2+MnSO4 = MnO2 + H2SO4

F.    H2O2 +     Fe2+ +     H+  ="="     Fe3+  +     H2O

(1)上述反应不属于氧化还原反应的是(填代号)_____________。

(2)H2O2仅体现还原性的反应是(填代号)                  

(3)H2O2既体现氧化性又体现还原性的反应是(填代号)             

(4)H2O2体现酸性的反应是(填代号)          

(5)上述反应说明H2O2、Ag2O、K2CrO4氧化性由强到弱的顺序是:                 

(6)通过以上反应分析, H2O2常称为绿色氧化剂,原因是_______________________。

(7)请配平化学反应F,并画出电子转移情况。

H2O2 +     Fe2+ +     H+  ="="     Fe3+  +     H2O

(8)由于H2O2有较强氧化性,能使某些有色试剂褪色,具有漂白作用,另外它还有弱酸性,某学生将H2O2溶液滴入含有酚酞的氢氧化钠溶液中,观察到溶液的红色消失。为了探究溶液褪色的原因,该学生提出了两种假设,然后又设计了一个简单的实验方案,以验证这两种假设。请回答:

(A)该学生提出的两种假设是:

假设①___________________________________________;

假设②   _________________________________      

(B)将该学生设计的简单实验方案、预测的实验现象及结论填入下表(结论部分只需填①或②):

简单实验方案预测的实验现象结论
  假设____成立
 假设____成立

题型:单项选择题

《史记》记载,刘邦称帝之后以旧礼尊其父,有人劝说刘父:“今高祖虽子,人主也,太公虽父,人臣也。奈何令人主拜人臣!如此则威重不行”。此后其父以尊礼待刘邦。从文中可以看出[ ]

A.刘邦违背了纲常伦理

B.宗法关系要服从于君权

C.汉初宗法制趋于崩溃

D.君臣关系等级森严

题型:单项选择题

For each blank in the following passage there are four words or phrases marked A, B, C and D. Fill in each blank with the word or phrase that best fits the context.

Music is nice, people seem to say, but not important. When students and parents are asked to rate subjects according to their importance, the music arts are   50   at the bottom of the list. Too often, music is viewed as mere entertainment, but certainly not an education which should be first taken into account. This view is   51  . In fact, music education is beneficial and important for all students.

Music tells us who we are. Because music is an expression of the beings who create it, it    52   their thinking and values, as well as the social   53   it came from. Rock music   54   a lifestyle just as surely as does a Schubert song. The jazz influence that George Gershwin and other musicians introduced into their music is obviously American because it came from American musical   55  . Music expresses our character and values. It gives us identity as a society.

Music provides a kind of feeling that cannot be   56   any other way.   57   can explain how the sun rises and sets. The arts explore the emotional meaning of the same phenomenon. We need every possible way to discover and   58   to our world for one simple but powerful reason: No one way can get it all.

The arts are forms of thought as powerful in what they communicate as mathematical and scientific symbols. They are ways we human being “talk” to each other. They are the   59   of civilization through which we express our fears, our curiosities, our hungers, our discoveries, our hopes. The arts are ways we give form to our ideas and imagination so that they can be   60    others. When we do not give children   61   to an important way of expressing themselves such as music, we   62   from them the meanings that music expresses.

Science and technology do not tell us what it means to be human. The   63   do. Music is an important way we express the meaning and value of peace and love.

So music education is far more   64   than people seem to realize.

50. A. embarrassedly        B. doubtfully            C. unavoidably          D. unexpectedly

51. A. aggressive         B. shortsighted       C. reasonable              D. instructive

52. A. reflects               B. promotes                      C. dominates         D. changes

53. A. position                     B. benefit                        C. standard                     D. environment

54. A. takes in           B. stands for            C. makes up                 D. looks through

55. A. instruments             B. families                      C. traditions                    D. seasons

56. A. acquired             B. understood         C. abandoned                 D. noticed

57. A. Music                        B. Entertainment    C. Mathematics                D. Science

58. A. stick                        B. refer                            C. lead                                  D. respond

59. A. means               B. languages           C. features                 D. achievements

60. A. compared with       B. imposed on         C. shared with              D. drawn from

61. A. solution                 B. access                        C. entrance                         D. direction

62. A. take away          B. set aside              C. draw up                     D. work out

63. A. musicians                 B. teachers                    C. courses                           D. arts

64. A. enjoyable         B. wasteful               C. necessary                       D. negative

题型:单项选择题

关于基金宣传推介材料登载过往业绩,下列说法正确的是( )。

A.基金合同生效不足6个月也可登载过往业绩

B.基金合同生效1年以上但不满10年的,只需登载最近1个完整会计年度的业绩

C.基金合同生效5年的,应当登载自合同生效当年开始所有完整会计年度的业绩

D.基金合同生效10年以上的,只需登载最近5个完整会计年度的业绩

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鼻咽部肿瘤()

A.颈外动脉栓塞

B.支气管动脉栓塞

C.髂内动脉栓塞

D.颌内动脉栓塞

E.内乳动脉栓塞

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