检查化合物纯度的方法包括A.高效液相色谱法  B.纸色谱法  C.薄层色谱法  D.

题型:多项选择题

问题:

检查化合物纯度的方法包括

A.高效液相色谱法 

B.纸色谱法 

C.薄层色谱法 

D.气相色谱法 

E.熔点测定 

考点:中药学(医学高级)中药学(医学高级)题库
题型:多项选择题
方程组
x+y=5k
x-y=9k
的解也是方程2x+3y=6的解,则k的值为______.
题型:多项选择题

a、b、c三个α粒子由同一点垂直场强方向进入偏转电场,其轨迹如图所示,其中b恰好飞出电场,下列说法正确的是(  )

A.在b飞离电场的同时,a刚好打在负极板上

B.b和c同时飞离电场

C.进入电场时,c的速度最大,a的速度最小

D.动能的增量相比,c的最小,a和b的一样大

题型:多项选择题

. Many people are quite at a loss as to what to do _______ a real fire.

A.in honor of

B.in need of

C.in case of

D.in form of

题型:多项选择题
把8:9的前项增加16,要使比值不变,后项应该(  )
A.加上16B.乘以16C.乘以3D.加上27
题型:多项选择题

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 is a statement about the disadvantages of standardized testing()

A. It will not improve the innate intelligence of the students

B. What is not tested is neglected by our education

C. It will cause negative political consequences for all schools

D. Testing can not control curriculum and instruction

更多题库