所有数据都满足数据完整性约束条件的状态，称为数据库的A．完整性 B．正确性 C．一致

如图所示，两条间距l＝1 m的光滑金属导轨制成倾角37°的斜面和水平面，上端用阻值为R＝4 Ω的电阻连接．在斜面导轨区域和水平导轨区域内分别有垂直于斜面和水平面的匀强磁场B₁和B₂，且B₁＝B₂＝0.5 T．ab和cd是质量均为m＝0.1 kg，电阻均为r＝4 Ω的两根金属棒，ab置于斜面导轨上，cd置于水平导轨上，均与导轨垂直且接触良好．已知t＝0时刻起，cd棒在外力作用下开始水平向右运动(cd棒始终在水平导轨上运动)，ab棒受到F＝0.6－0.2t(N)沿斜面向上的力作用，处于静止状态．不计导轨的电阻．

(1)求流过ab棒的电流I_ab随时间t变化的函数关系；

(2)分析并说明cd棒在磁场B₂中做何种运动；

(3)t＝0时刻起，1 s内通过cd棒的电荷量q为多少？

(4)若t＝0时刻起，1.2 s内作用在cd棒上外力做功为W＝16 J，则这段时间内电阻R上产生的焦耳热Q_R多大？

无风流条件下移线定位时，若第一次观测物标的舷角为（），第二次观测物标的舷角为（），则两次观测之间的航程即为该物标的正横距离。

Ⅰ．26°.5，45°；Ⅱ．45°，90°；Ⅲ．22°.5，45°。

A．Ⅰ，Ⅱ

B．Ⅰ，Ⅲ

C．Ⅱ，Ⅲ

D．Ⅰ，Ⅱ，Ⅲ

私密模式将私密联系人的短信，通话记录等信息加密保存到本地，只有输入正确的密码才能查看相关信息，私密界面完全隐藏，有效的保护您的个人隐私信息。

安全验收评价中，要求根据建设项目或工业园区建设的实际情况选择适用的评价方法。同时，要做符合性评价以及事故发生的可能性及其严重程度的预测。下列内容属于符合性评价内容的是( )

A．被评价建设项目安全设施“三同时”
B．被评价建设项目或工业园区可能发生事故的类型及其严重程度
C．针对可能出现的事故，提出相应的安全措施
D．分析存在的危险、有害因素类型及其危害性

As a professor at a large American university, there is a phrase that I hear often from students: "I’m only a 1050. "The unlucky students are speaking of the score on the Scholastic Aptitude Test (SAT), which is used to determine whether they will be admitted to the college or university of their choice, or even have a chance to get a higher education at all. The SAT score, whether it is 800, 1100 or 1550, has become the focus at this time of their life.

It is obvious that if students value highly their test scores, then a great amount of their serf-respect is put in the number. Students who perform poorly on the exam are left feeling that it is all over. The low test score, they think, will make it impossible for them to get into a good college. And without a degree from a prestigious university, they fear that many of life’s doors will remain forever closed.

According to a study done in the 1990s, the SAT is only a reliable indicator of a student’s future performance in most cases. Interestingly, it becomes much more accurate when it is set together with other indicators—like a student’s high school grades. Even if standardized tests like the SAT can show a student’s academic proficiency, they will never be able to test things like confidence, efforts and willpower, and are unable to give us the full picture of a student’s potentialities (潜力). This is not to suggest that we should stop using SAT scores in our college admission process. The SAT is an excellent test in many ways, and the score is still a useful means of testing students. However, it should be only one of many methods used.

A "prestigious university" is most probably （）.

A．a famous university

B．a technical university

C．a traditional university

D．an expensive university