如图是a、b两种固体物质的溶解度曲线,说法不正确的是下列( ) A.20℃时,

题型:选择题

问题:

如图是a、b两种固体物质的溶解度曲线,说法不正确的是下列(  )

A.20℃时,a、b的饱和溶液中溶质质量分数相等

B.a中混有少量的b,可以用降温结晶法提纯a

C.a的溶解度比b大

D.b的溶解度都随温度升高而增大

考点:固体溶解度结晶
题型:选择题

下列各句中,没有语病的一句是[ ]

A.那烟雨中的柳叶湖,恰如一幅淡雅而隽永的水墨画,展现出她别样的风姿。    

B.在即将举行的广州亚运会上,体育健儿们纷纷表示一定充分发扬自身水平。    

C.为了防止甲型H1N1流感病毒不再蔓延,我国政府采取了强有力的应对措施。    

D.我永远不会忘记老师耐心细致地纠正并指出我考试中的问题的情景。

题型:选择题

施工进度计划反映了最佳施工方案在( )上的具体安排。

A.程序

B.技术

C.时间

D.空间

题型:选择题

Many theories concerning the causes of juvenile delinquency(crimes committed by young people) focus either on the individual or on society as the major contributing influence. Theories (91) on the individual suggest that children engage in criminal behavior (92) they were not sufficiently penalized for previous misdeeds or that they have learned criminal behavior through (93) with others. Theories focusing on the role of society suggest that children commit crimes in (94) to their failure to rise above their socioeconomic status, (95) as a rejection of middle, class values.
Most theories of juvenile delinquency have focused on children from disadvantaged families, (96) the fact that children from wealthy homes also commit crimes. The latter may commit crimes (97) lack of adequate parental control. All theories, however, are tentative and are (98) to criticism.
Changes in the social structure may indirectly (99) juvenile crime rates. For example, changes in the economy that (100) to fewer job opportunities for youth and rising unemployment (101) make gainful employment increasingly difficult to obtain. The resulting discontent may in (102) lead more youths into criminal behavior.
Families have also (103) changes these years. More families consist of one-parent households or two working parents; (104) , children are likely to have less supervision at home (105) was common in the traditional family (106) . This lack of parental supervision is thought to be an influence on juvenile crime rates. Other (107) causes of offensive acts include frustration or failure in school, the increased (108) of drugs and alcohol, and the growing (109) of child abuse and child neglect. All these conditions tend to increase the probability of a child committing a criminal act, (110) a direct causal relationship has not yet been established.

A.case

B.short

C.turn

D.essence

题型:选择题

下列说法不正确的是

A.化学反应有新物质生成,并遵循质量守恒定律和能量守恒定律

B.原子吸收光谱仪可用于测定物质中的金属元素,红外光谱仪可用于测定化合物的官能团

C.分子间作用力比化学键弱得多,但它对物质熔点、沸点有较大影响,而对溶解度无影响

D.酶催化反应具有高效、专一、条件温和等特点,化学模拟生物酶对绿色化学、环境保护及节能减排具有重要意义

题型:选择题

在外圆磨削时,()最大。

A.切向力

B.径向力

C.轴向力

D.摩擦力

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