试题与答案

铬不锈钢氧化法冶炼与返吹法冶炼在操作中最突出的问题是()。A.成份的控制 B.温度的

题型:单项选择题

题目:

铬不锈钢氧化法冶炼与返吹法冶炼在操作中最突出的问题是()。

A.成份的控制

B.温度的控制

C.对碳的控制

答案:

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参考答案:(1)归纳式理论:以数据为基础,把数据反映的实际关系组织为理论原则;(2)演绎式理论:从理论解释出发,寻求数据以检验理论的预测。(3)机能式理论:综合了归纳与演绎两种成分,强调数据,也重视演...

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After graduating form high school, people rarely multiply fractions or discuss ancient Rome, but they are confronted daily with decisions relating to home economics. Yet whereas mathematics and history are required courses in the high school curriculum, home economics is only an elective, and few students choose to take it.
Which of the following positions would be best supported by the considerations above

A.If mathematics and history were not required courses, few students would choose, to take them.

B.Whereas home economics would be the most useful subject for people facing the decisions they must make in daily life, often mathematics and history can also help them face these decisions.

C.If it is important to teach high school students subjects that relate to decisions that will confront them in their daily lives, then home economics should be made an important part of the high school curriculum.

D.Mathematics, history, and other courses that are not directly relevant to a person’s daily life should not be a required part of the high school curriculum.

E.(E) Unless high schools put more emphasis on nonacademic subjects like home economics, people graduation from high school wilt never feel comfortable about making the decisions that will confront them in their daily lives.

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如图所示(俯视),MN和PQ是两根固定在同一水平面上的足够长且电阻不计的平行金属导轨,两导轨间距L=0.2m,其间有一个方向垂直水平面竖直向下的匀强磁场B1=5.0T.导轨上NQ之间接一电阻R1=0.40Ω,阻值为R2=0.10Ω的金属杆垂直导轨放置并与导轨始终保持良好接触.两导轨右端通过金属导线分别与电容器C的两极相连.电容器C紧挨带有小孔的固定绝缘弹性圆筒,圆筒壁光滑,筒内有垂直水平面竖直向下的匀强磁场B2,O是圆筒的圆心,圆筒的内半径r=0.40m.

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(2)计算金属杆匀速运动时电容器两极板间的电势差;

(3)当金属杆处于(1)问中的匀速运动状态时,电容器C内紧靠极板D处的一个带正电的粒子加速后从a孔垂直磁场B2并正对着圆心O进入圆筒中,该带电粒子与圆筒壁碰撞两次后恰好又从小孔a射出圆筒.已知该带电粒子每次与筒壁发生碰撞时电量和能量都不损失,不计粒子的初速度、重力和空气阻力,粒子的荷质比

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