如图所示,水平面上的平行粗金属导轨MN与PQ的左端连接一个定值电阻R,导体棒ab

题型:选择题

问题:

如图所示,水平面上的平行粗金属导轨MNPQ的左端连接一个定值电阻R,导体棒ab可以在导轨上无摩擦地滑动,滑动过程中总保持与导轨垂直,并且接触良好.空间存在着方向竖直向上的匀强磁场,磁感强度为Bab棒的电阻为r,两导轨间距为d,导轨电阻不计.用水平向右的恒定拉力F拉动ab棒,稳定后作匀速运动的速度v=5.0m/s.只进行如下的哪项改变,可以使ab棒稳定后作匀速运动的速度v变为2.5m/s?

A.磁感强度B的大小减半

B.力F大小减半

C.电阻R减半

D.导轨间距d减半 

考点:电磁感应现象的综合应用
题型:选择题

油炸食物不宜多吃,因为食物长时间煎炸后会产生微量的丙烯醛(化学式为C3H4O)等有毒物质,损害人体健康。下列有关丙烯醛的说法中,不正确的是 [ ]

A.该物质由碳、氢、氧三种元素组成

B.该物质中碳、氢、氧元素间的质量比是9﹕1﹕2

C.该物质的分子中原子个数比依次为3﹕4﹕1

D.该物质不是氧化物

题型:选择题

第四部分写作(共两节,满分20分)
第一节任务型读写(共10小题;每小题1分,满分10分)
阅读下面短文,根据所读内容在表格中的空白处填入恰当的单词。注意:每个空格只填一个单词。
In a society, such as the United States or Canada, which has many national, religious and cultural differences, people highly value individualism-the difference among people. Teachers place a lot of importance on the qualities that make each student special. The educational systems in these countries show these values. Students don't memorize information. Instead, they work individually and find answers themselves. There is often discussion in the classroom. At an early age, students learn to form their own ideas and opinions.
In most Asian societies, by contrast, people have the same language, history, and culture. Perhaps for this reason, the educational system in much of the Orient reflects society’s belief in group goals and purposes rather than individualism. Children in China, Japan, and Korea often work together and help one another in assignments. In the classroom, the teaching methods are often very formal. The teacher lectures, and the students listen. There is not much discussion. Instead, the students recite rules of information that they have memorized.
There are advantages and disadvantages to both of these systems of education. For example, one advantage to the system in Japan is that there much more math and science than American students learn by the end of high school. They also study more hours each day and more days each year than North Americans do. The system is difficult, but it prepares students for a society that values discipline and self-control. There is, however, a disadvantage. Memorization is an important learning method in Japanese schools, yet many students say that after an exam, they forget much of the information that they have memorized.
The advantage of the educational system in North American, on the other hand, is that students learn to think for themselves. The system prepares them for a society that values creative ideas. There is, however, a disadvantage. When students graduate from high school, they haven’t memorized as many basic rules and facts as students in other countries have.
Title:  66  of Educational System between North America and Asia
 
Students in the US and  67  
Students in China, Japan and Korea
What do they
  68   
Individualism
    69   goals and purposes
Different
  70 of study
Working individually
Listening to the teachers
Forming their own ideas and opinions
Reciting rules and memorizing information
A lot of discussion in the classroom
Not much discussion
  71   
Learning to think for themselves
Learning much more math and science
Studying more hours each day and more days each year
Good for a society that values  72 
Good for a society valuing
  73  and self-control
Disadvantages
Students haven’t memorized many basic rules and facts before 74 
Information is  75  easily.
题型:选择题

核心系统中格式位是0代表是()

A、有折

B、无折

C、有折到挂息

D、变更账户明细

题型:选择题

在项目不受资金约束的情况下,一般采用( )。

A.净现值比较法

B.净年值比较法

C.差额投资内部收益率法

D.差额投资回收期法

E.差额投资收益率法

题型:选择题

Directly he saw her, he fell ______ in love.

A.from head to foot

B.head over heels

C.head and shoulders

D.toe to toe

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