搜题请搜索小程序“爱下问搜题”
问题 实验题

在做研究平抛运动的实验时，让小球多次沿同一轨道运动，通过描点法画出小球平抛运动的轨迹。

（1）为了能较准确地描绘运动轨迹，下面列出一些操作要求，将你认为正确选项的前面字母填在横线上：___________。

A. 通过调节使斜槽的末端保持水平

B. 每次释放小球的位置必须不同

C. 每次必须由静止释放小球

D. 小球运动时不应与木板上的白纸（或方格纸）相接触

E. 将球的位置记录在纸上后，取下纸，用直尺将点连成折线

（2）在该实验中，某同学记录了A、B、C三点，取A点为坐标原点，建立了如图所示的坐标系。平抛轨迹上的这三点坐标值图中已标出。那么A、B两点的时间间隔是___________，小球平抛的初速度为___________。

答案

（1）ACD

（2）0.1s，1m/s

单项选择题

某公司的婴幼儿润肤产品由“宝宝用好”到“宝宝用好，您用也好”的定位转变，使其目标市场在婴幼儿市场的基础上，又增加了中青年女性市场，产品销售量也因此而得以增长，这种产品成熟期的战略是（ ）

A．调整品牌

B．调整市场

C．调整产品

D．调整投资
查看答案
单项选择题

A new study finds that blacks on death row (1) of killing whites are more likely to be executed than whites who kill minorities. It also concludes that blacks who kill (2) minorities are (3) likely to be executed than blacks who kill whites. For example, there is more than a twofold greater risk that an African-American who killed a white will be executed than a white person who kills a (4) victim. A Hispanic is at least 1.4 (5) more likely to be executed (6) such an offender kills a white.

The researchers of the study believe that there are two (7) explanations.. First, prosecutors often win (8) office if they win well-publicized cases. When a black kills a white, such killings gets more (9) and this idea can be (10) by many famous cases. (11) , the court judges at the state level are often (12) to elections, called retention elections. Retention election or judicial retention within the United States court system, is a periodic process, in which the voter (13) approval or disapproval for the judges presently (14) their position, and a judge can be removed from the position if the (15) of the citizens vote him or her out. Just as the researchers (16) out, death penalty is (17) political.

The findings of the study, in short, show that American justice systems clearly (18) white lives more than those of blacks or Hispanics. The researchers also say their findings (19) serious doubts about (20) that the U.S. criminal justice system is colorblind.

20（）

A.dissertations

B.affirms

C.claims

D.suggestions
查看答案