静电喷漆技术具有效率高、浪费少、质量好、有利于工人健康等优点,其装置示意图如图所

题型:计算题

问题:

静电喷漆技术具有效率高、浪费少、质量好、有利于工人健康等优点,其装置示意图如图所示。A、B为 两块平行金属板,间距d=0.30m,两板间有方向由B指向A、电场强度E=1.0×103 N/C的匀强电场,在A板的中央放置一个安全接地的静电油漆喷枪P,油漆喷枪的半圆形喷嘴可向各个方向均匀地喷出带电油漆微粒,油漆微粒的质量m=2.0×1015kg、电荷量q= -2.0×10-15 C,喷出的初速度v0=2.0m/s。油漆微粒最后都落在金属板B上,微粒所受重力和空气阻力以及微粒之间的相互作用力均可忽略。求:

(1)微粒落在B板上的动能;

(2)微粒从离开喷枪后到达B板所需的最短时间;

(3)微粒最后落在B板上所形成图形的面积。

考点:带电粒子在电场中的加速
题型:计算题

解方程:3.1x-0.6x=1

题型:计算题

急性胰腺炎的局部并发症有()

A.胰腺脓肿

B.胰腺纤维化

C.胰腺萎缩

D.胰腺钙化

E.胰腺假性囊肿

题型:计算题

一急性横贯性脊髓炎是指()。

A.脊髓白质脱髓鞘或坏死所致的急性横贯性损害

B.椎管内占位性病变而引起的脊髓受压

C.脊髓血管的发育异常

D.脊髓先天发育异常,胚胎期神经管关闭不全

E.维生素B

题型:计算题

学龄前儿童最常采用的饮食制度是()。

A.三餐制

B.三餐三点制

C.三餐两点制

D.三餐一点制

E.三餐四点制

题型:计算题

The earliest evidence of standardized testing based on merit comes from China during the Han dynasty. The concept of a state ruled by men of ability and virtue was an outgrowth of Confucian philosophy. Standardized testing has not traditionally been a part of European pedagogy. Based on the skeptical and open-ended tradition of debate inherited from Ancient Greece, Western academia favored the essay. The use of standardized testing in the United States is a 20th century phenomenon with its origins in World War I.

One of the main advantages of standardized testing is that the results can be empirically documented ; therefore the test scores can be shown to have a relative degree of validity and reliability, as well as results which are generalizable and replicable. This is often contrasted with grades on a school transcript, which are assigned by individual teachers. Another advantage is aggregation. A well designed standardized test provides an assessment of an individual’s mastery of a domain of knowledge or skill which at some level of aggregation will provide useful information.

Though many educators recognize that standardized tests have a place in tools used to assess student achievement, critics feel that overuse and misuse of these tests is having serious negative consequences on teaching and learning. The temptation is to use the tests to define curriculum and focus instruction. What is not tested is not taught, and how the subject is tested becomes a model for how to teach the subject. Moreover, standardized test scores are problematic tools for school accountability because the examinee scores are influenced by three things: what kids learn in school, what kids learn outside of school, and innate intelligence. Critics believe this is not possible. While it is possible to use a standardized test and not let its limits control curriculum and instruction, this can result in a school putting itself at risk for producing lower test scores, with negative political consequences.

Some critics say that some children do not do well on standardized tests, despite mastery of the material, due to testing anxiety or lack of time management or test-taking skills. This reflects the fact that tests cannot directly measure student knowledge, only the ability of students to apply knowledge in a stressful situation.

Some parents are willing to pay thousands of dollars to prepare their children for tests, a financial barrier that may give children of more wealthy parents an advantage compared to less affluent families. However this criticism would probably apply even more to testing alternatives such as portfolios or essays. Many studies also show that test coaching has little effect on scores on well-buih tests. The ability of wealthy families to pay for higher-quality education is not specifically related to standardized testing.

Which one of the following factors influencing test scores is NOT criticized by some critics()

A. A good job in mastering what is tested

B. The feeling of anxiety during tests

C. Failure to have a good time arrangement

D. Skills to get a high score in tests

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