问题 单项选择题

对线性表进行二分法查找,其前提条件是

A.线性表以顺序方式存储,并且按关键码值排好序

B.线性表以顺序方式存储,并且按关键码值的检索频率排好序

C.线性表以链接方式存储,并且按关键码值排好序

D.线性表以链接方式存储,并且按关键码值的检索频率排好序

答案

参考答案:A

解析: 二分查找法又称折半查找法,它只能用于顺序存放并且已经排好序的线性表。

填空题

(12分)I.描述弱电解质电离情况可以用电离度和电离平衡常数表示,下表1是常温下几种弱酸的电离平衡常数(Ka)和弱碱的电离平衡常数(Kb)。表1                                     

酸或碱电离平衡常数(Ka或 Kb
CH3COOH1.8×10-5
HNO24.6×10-4
HCN5×10-10
HClO3×10-8
NH3·H2O1.8×10-5
请回答下列问题:

上述四种酸中,酸性最弱的是                 (用化学式表示)。下列能使醋酸溶液中CH3COOH的电离程度增大,而电离平衡常数不变的操作是         (填序号)。

A.升高温度

B.加水稀释           

C.加少量的CH3COONa固体

D.加少量冰醋酸

II.氮是地球上含量最丰富的一种元素,氮及其化合物在工农业生产.生活中有着重要作用。请回答下列问题:(图中涉及物质为气态)

(1)上图是1 mol NO2和1mol CO反应生成CO2和NO过程中能量变化示意图,请写出NO2和CO反应的热化学方程式                                             

(2)在0.5L的密闭容器中,一定量的氮气和氢气进行如下化学反应:

N2(g)+3H2(g)2NH3(g)△H<0,其化学平衡常数K与温度t的关系如下表:请完成下列问题。

t/℃200300400
KK1K20.5
①试比较K1.K2的大小,K1_     K2(填写“>”.“=”或“<”)。

②下列各项能作为判断该反应达到化学平衡状态的依据是____(填序号字母):

a.容器内N2.H2.NH3的浓度之比为1:3:2     b.v(N2=3v(H2

c.容器内压强保持不变                         d.混合气体的密度保持不变

③在400℃时, 当测得NH3和N2.H2的物质的量分别为1mol和2mol.3mol时,则该反应的v(N2_          _ v(N2(填写“>”.“=”或“<”)

完形填空

III.Reading Comprehension

Section A

Directions: 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 fits the context.

A detailed study of biological diversity(多样性)in town and city gardens has found that they offer a vital refuge for animals and plants. It has also fund that many of the ideas about wildlife gardening are not  50  .In fact, small gardens are just as good as big gardens at  51 wildlife, suburban gardens are not always better than city gardens and non-native plants are not always harmful to native insects and birds. Britain’s 16,000,000 gardens are a refuge for hundreds of species of animals and plants that would find it  52   to survive onintensively (精细地)farmed land. According to the study, gardens are amazingly varied even compared to   53  environments that are good for wildlife. Small gardens are more interesting  54 they vary a great deal in botanical environment, All the wildlife responds to the variation.

Ken Thompson of Sheffield University was involved n the first detailed study of the  55  living in British gardens when he and his colleagues surveyed 61 gardens in Sheffield. They really found a(n)  56 diversity of plants and animals. They also identified a range of simple   57  that improved a garden’s environment for wildlife. The top thing is to grow more big trees as these greatly  58  the volume of vegetation in the garden and a lot of  59 means a lot of places to live and a lot of things to eat.   60  , create a pond for insects and frogs. Think before stocking it with fish which will eat insect eggs. Also, it is not wise to light up the garden at night with bright lawn lamps, which will  61 many night creatures, Finally, don’t be too tidy: don’t be  62  to clear up everything when the garden stops flowering. Just   63 a bit of things lying around.

To sum up, people who want to turn their gardens into wildlife refuges should  64  and let the grass grow tall, the flowers turn to seed and trees expand skyward.

50.A.true          B.basic         C.vivid         D.simple

51.A.selecting      B.importing     C.offering       D.attracting

52.A.impossible       B.illegal          C.lucky         D.convenient

53.A.peaceful      B.warm              C.natural         D.clean

54.A.before         B.unless          C.but           D.because

55.A.wildlife       B.men         C.germ         D.pet

56.A.confusing     B.complete      C.surprising     D.orderly

57.A.measures     B.standards     C.services       D.functions

58.A.occupy        B.increase       C.limit         D.reduce

59.A.vegetation     B.reservation       C.preparation      D.decoration

60.A.By contrast      B.As a result          C.In other words  D.In addition

61.A.block          B.disturb         C.benefit         D.protect

62.A.in a mess     B.in a way      C.in a hurry     D.in a while

63.A.forget          B.remove        C.avoid         D.leave

64.A.escape         B.relax         C.strive         D.retire