试题与答案

如图所示,理想变压器原、副线圈的匝数比为10:1,b是原线圈的中心接头,电压表V

题型:选择题

题目:

如图所示,理想变压器原、副线圈的匝数比为10:1,b是原线圈的中心接头,电压表V和电流表A均为理想电表.从某时刻开始在原线圈c、d两端加上交变电压,其瞬时值表达式为u=220sin100πt(V).下列说法正确的是(  )

A.当单刀双掷开关与a连接时,电压表的示数为22V

B.当单刀双掷开关与b连接时,电压表的示数为11V

C.当单刀双掷开关与a连接,滑动变阻器触头P向上移动的过程中,电压表的示数不变,电流表的示数变大

D.单刀掷开关由a扳向b时(滑动变阻器触头P不动),电压表和电流表的示数均变大

答案:

答案:D

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题型:选择题

木糖醇是目前市场上的一种蔗糖替代品,在某些温度下其溶解度分别为:30℃时为70g,50℃时为84g,60℃时为90g。右图表示的是木糖醇等固体的溶解度曲线。根据曲线判断,下列说法不正确的是

A.X为木糖醇的溶解度曲线

B.随着温度的升高,Z物质的溶解度逐渐减小

C.可以采用冷却热饱和溶液的方法获得Z的晶体

D.50℃时,Y的饱和溶液和Z的饱和溶液溶质的质量分数相等

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题型:单项选择题

The first and most important agents of socialization are the people who care for infants. In the earliest months, messages from nurturers constitute the child’s basic understanding of the world around it. This is the infant’s first introduction to the language that shapes perception and elicits emotion.
Another powerful source of information and socialization is the friendship of peers. Peers are equals that one can deal with on the same level as oneself, whereas parents are superiors. The heavy emotional overlay of family relationships makes some kinds of learning difficult.
Much formal socialization is placed in the hands of professionals. Teachers from kindergarten on are specifically designated agents of socialization. Ideally, a teacher is one who has both knowledge and the skills to present it. During the course of teaching their subjects, classroom instructors provide role models and attempt to convey the excitement of learning itself.
In earlier times, parents, friends and teachers would comprise the list of primary childhood socializers. Children’s books, comics and magazines might also have been mentioned as sources of information on norms and role models. Today one must add three powerful indirect or nonpersonal socialization agents: radio, movies and television. Many people learn about politics, form a vision of well-being, and develop attitudes towards others from what they see on the screen and hear through the speakers.

Which of the following statements is NOT implied in the passage

A.Teachers are sociable.

B.Teachers are role models.

C.Teachers are paid agents of socialization.

D.Teachers are knowledgeable and skillful.

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