5.对以下漫画的寓意,理解不恰当的一项是( )
A.中国500强企业没有美国500强企业有竞争力。
B.中国500强企业有贪图虚名、急功近利的毛病。
C.中国500强企业不能敦本务实,有以体量取胜的心态。
D.中国500强企业与美国500强企业都重攀比。
实验室以含有Ca2+、Mg2+、Cl-、SO、Br-等离子的卤水为主要原料制备无水CaCl2和Br2,流程如下:
(1)操作Ⅰ使用的试剂是____________,所用主要仪器的名称是________。
(2)加入溶液W的目的是______________。用CaO调节溶液Y的pH,可以除去Mg2+。由表中数据可知,理论上可选择的pH最大范围是____________。酸化溶液Z时,使用的试剂为__________。
开始沉淀时的pH | 沉淀完全时的pH | |
Mg2+ | 9.6 | 11.0 |
Ca2+ | 12.2 | c(OH-)=1.8 mol·L-1 |
(3)实验室用贝壳与稀盐酸反应制备并收集CO2气体,下列装置中合理的是__________。
(4)常温下,H2SO3的电离常数Ka1=1.2×10-2,Ka2=6.3×10-8;H2CO3的电离常数Ka1=4.5×10-7,Ka2=4.7×10-11。某同学设计实验验证H2SO3的酸性强于H2CO3:将SO2和CO2气体分别通入水中至饱和,立即用酸度计测两溶液的pH,若前者的pH小于后者,则H2SO3酸性强于H2CO3。该实验设计不正确,错误在于___________________________。
用一个化学方程式表示H2SO3酸性强于H2CO3: __________________。
定长为3的线段的两个端点
分别在
轴,
轴上滑动,动点
满足
.
(1)求点的轨迹曲线
的方程;
(2)若过点的直线与曲线
交于
两点,求
的最大值.
我国古代青花瓷绘画装饰清秀素雅,各个时期均有鲜明的时代特征。其中,元青花绘画精美生动,其纹样特点既带有一些西亚美术的装饰形式,又带有浓厚的中国民间图案的面貌,布局繁密,风格华丽,与当时织金锦的图案和效果极为相似.元青花的特点表明
①事物之间联系的客观性制约着人的主观能动性的发挥
②任何事物的存在和发展都离不开特定的历史条件
③矛盾的特殊性构成了一事物区别于他事物的特殊本质
④实践活动的社会历史性决定着认识活动的无限性
下列与激素及信号分子相关的叙述,正确的是()
A. 所有的活细胞都能产生酶,但只有内分泌腺的细胞会合成激素
B. 细胞产生的激素、淋巴因子以及神经递质等都属于信号分子,在细胞间起到传递信息的作用
C. 促甲状腺激素释放激素的靶细胞是垂体,促甲状腺激素的靶细胞是甲状腺,甲状腺激素的靶细胞是垂体和下丘脑
D. 激素间的作用包括协同与拮抗作用,促甲状腺激素与促甲状腺激素释放激素、甲状腺激素间的关系属于协同关系;胰岛素与胰高血糖素间具有拮抗作用
生物变异的根本来源是()
A.基因重组 B. 染色体数目变异
C.染色体结构变异 D. 基因突变
2021年5月16日,联合国安理会举行巴以冲突问题紧急会议。中国外长王毅表示,巴勒斯坦独立建国权利受到持续侵害,人民的困境进一步加深,安理会必须就巴以冲突采取有力行动,推动局势尽快降温。这表明( )
A.联合国不得干涉在本质上属于任何国家内政的事务
B.联合国安理会拥有广泛职权,是联合国主要审议机构
C.联合国安理会的每一个理事国均有“否决权”
D.联合国安理会负有维护世界和平与安全的主要责任
如图,在四棱柱中,
,底面
为菱形,点
分别是
的中点,且
。
(I)求证:;
(II)求三棱锥的体积。
毛泽东对中国革命的性质、对象、任务、动力和前途等一系列问题进行系统论述的时间和著作是 ( )
A.大革命时期的《中国社会各阶级的分析》等
B.井冈山时期的《星星之火,可以燎原》等
C.延安时期的《新民主主义论》等
D.共和国时期的《论十大关系》等
I'm glad I went over all my notes;otherwise_______.
A.I’d have failed B.I'd fail C.I may have failed D.I'll have failed.
在某一恒温体积可变的密闭容器中发生如下反应:
时刻达到平衡后,在
时刻改变某一条件,其反应过程如右图所示。下列说法正确的是
A.
B.I、Ⅱ两过程达到平衡时,A的体积分数I>II
C.时刻改变的条件是向密闭容器中加C
D.I、II两过程达到平衡时,平衡常数I<II
Former Irish President Mary Robinson was just making a polite conversation with an Ethiopian(埃塞俄比亚的) teenager about her wedding day. The 16-year-old had already been married for a year."She looked at me with the saddest eyes and said, 'I had to drop out of school,'" Robinson said in a telephone interview."That conveyed to me the reality, "said Robinson, the first woman to serve as Ireland's president and former U.N.high commissioner for human rights."Her life, as far as she is concerned, had more or less ended."
Robinson said keeping girls in school was one of the most important things policymakers could do to address the coming challenges of an ever-increasing population, predicted by the United Nations to reach 7 billion soon."European countries are concerned about aging populations as is Japan, but this is much less of an issue than the huge number of people which we are going to see over the next 40 years when the population goes from 7 billion to 9 billion, "she said."Almost all of that increase will be in poor developing countries, so that we have a very big challenge."
Family planning experts worry in particular about the future population explosion in sub-Saharan Africa.In May, the United Nations projected the world population would reach 9.3 billion in 2050 and 10.1 billion by 2100. Much of that growth will come from Africa, where the population is growing at 2.3 percent a year—more than double Asia' s 1 percent growth rate. If that rate stays consistent, which is not certain, Africa's population will reach 3.6 billion by 2100 from the present 1 billion.
Joel Cohen, a professor of population studies at Rockefeller University and Columbia University in New York, said universal secondary education offered a way to reduce population in high birth-rate regions. In addition to providing information about birth control, a secondary education teaches women to reduce their own fertility(生育力), improve the health of their children and allows them to move from a mind-set of having many children, in the hopes that some will survive to improving the quality of each child's life, Cohen wrote in the journal Nature.
59. In the first paragraph, the author introduces his topic by_____.
A. explaining the author's opinions B. giving an example
C. describing the poor education system D. coming straight to the topic
60. What can we learn from the passage?
A. Robinson is happy after talking to the Ethiopian girl.
B. Robinson is a successful expert in population studies.
C. Robinson is worried about population growth.
D. Robinson encourages female education.
61. What is Joel Cohen's view about secondary education?
A. It provides basic knowledge of health.
B. It improves the health of children.
C. It makes people pay more attention to education.
D. It can change people's parenting ideas.
62. According to the passage, the most important way to control high population growth is .
A. keeping girls in school B. letting girls go away from Africa
C. letting young girls remain single D. keeping girls in families
如图所示,正方体ABCD﹣A′B′C′D′的棱长为1,E,F分别是棱AA′,CC′的中点,过直线E,F的平面分别与棱BB′、DD′交于M,N,设BM=x,x∈[0,1],给出以下四个命题:
①平面MENF⊥平面BDD′B′;
②当且仅当x=时,四边形MENF的面积最小;
③四边形MENF周长L=f(x),x∈[0,1]是单调函数;
④四棱锥C′﹣MENF的体积V=h(x)为常函数;
以上命题中假命题的序号为
A.①④ B.② C.③ D.③④
用如图甲所示实验装置,测量滑块与木板之间的动摩擦因数.长木板一端放在水平桌面上,另一端架在垫片上,在木板上B处放置一光电门,用光电计时器记录滑块上挡光片通过光电门时挡光的时间.实验中通过改变垫片的数量来改变木板倾角,从而进行多次测量.
(1)用游标卡尺测得挡光片的宽度如图乙所示,则遮光片的宽度为 mm;
(2)若挡光片的宽度为L,挡光片通过光电门的挡光时间为t,则滑块通过B点时的速度为;
(3)让滑块从A点从静止滑下,通过B点的速度为V.已知AB两点的高度差为H,两点间的距离为S,则滑块与木板间的动摩擦因数为(用H、V、S、g表示).
下列是对生物实验的一些叙述,正确的是( )
A、斐林试剂和双缩脲试剂的配方不同,但使用方法相同
B、吡罗红使DNA呈现红色,甲基绿使RNA呈现绿色
C、紫色洋葱鳞叶表皮细胞发生质壁分离时,能观察到紫色中央液泡逐渐缩小,颜色加深。
D、用高倍镜下观察植物细胞的有丝分裂,可看到纺锤体逐渐消失和赤道板形成