题干

学校里有30间教室,每间教室需装4盏“220V,60W”的白炽灯,那么在学校教室照明电路的总保险盒中,应选用的保险丝的规格是(     )           

A:额定电流为20A

B:额定电流为25 A

C:额定电流为30A

D:额定电流为35A

上一题 下一题 0.0难度 选择题 更新时间:2012-10-10 04:14:01

答案(点此获取答案解析)

D

同类题3

议论文阅读

抓住你的暗时间

刘未鹏

       ①每个人的手表都走得一样快,但每个人的生命却不是。大脑也是如此。衡量一个人生活了多少年,应该用他的思维时间来计算。所谓暗时间,即一个人用来思维的内在时间。举一 个极端的例子,如果一个人一出生就呆在一个特殊的保护室里,没有社会交往,没有知识获 取途径,18年后,你会不会认为他成年了?

       ②时间对每个人是均等的是一个错觉。如果你正在学习一门专业,你用自己所花费 的天數来衡量,很容易认为投入了不少时间。然而其实,实际投入的是时间和效率的乘积。你 可以“投入”很多时间在一件事情上面,却发现毫无进展。因为你没有把你要做的事、要学的 东S當驻在大脑中,时刻给予它最高的优先级。如果你走路吃饭做梦,心心念念想的都是这﹣事,你的思维时间就被利用到了极致,投入的时间才真正等于实际流失的时间。

       ③我们每个人的生命像沙漏,沙漏里装的沙子总量是相当的,不同的是,有的沙漏颈部 较扫,有些较粗。那些颈部较细的沙漏能够抓住每一粒时间之沙,虽然沙子总量一样,但相对 扣拥有更长的生命。能够充分利用暗时间的人将无形中多出一大块生命。

       ④程序员们都知道,任务切换需要耗费额外的花销。如果一个系统不停地在多个任务间 来回倒腾,就会消耗大量的时间。相比之下,如果只做一件任务,就不会有此损失。这就是为 什么专注的人比不专注的人。在时间利用效率上高得多的原因。

       ⑤另外,大脑在开始一件任务时,必须有一定的时间来“热身”。举个例子,你看了一会儿书,感到无聊,忍不住打开浏览器,10分钟后你想起来还要继续看书,但要回复到当时的状态 却需要一段时间把记忆中相关的内容再次激活。如果这个“热身”状态需要一刻钟,那么看似10分钟的上网,其实就花了25分钟。

       ⑥要充分利用暗时间,不仅要迅速进入状态,还要看能保持状态多久。

       ⑦很多人都有这样的体验,工作时,要处理的事情很多。另一方面,即便能够把任务的优 先级分配得比较合理,也难免在做一件事时心里还惦记着另一件事。

       ⑧这就涉及最后一个高效的习惯:抗干扰。只有具备高强的抗干扰能力,才能有效地利 用暗时间。抗干扰能力可以通过练习获得。事实证明,在有干扰的环境中,比如公交车上看 书,是锻炼专注能力的一个好办法。

(摘自《青年文摘》2012年第15期)

同类题5

任务型阅读

    Homework is a major part of going to school: It's your teachers' way of evaluating(评价) how much you understand of what's going on in class.____ Luckily, you can do a few things to make homework less work.

    Be sure you understand the homework.

    Write your homework down in your notebook or day planner if you need to.____It's much easier to take a minute to ask the teacher during or after class than to struggle to remember later that night!

    Use any extra time in school.

    Many schools have study halls that are specifically designed to allow students to study. It's tempting(诱惑) to hang out with friends during study periods or unstructured(松散的) time.____

    Take a break.

    ____ So take some breaks while doing your homework. Sitting for too long without stretching or relaxing will make you less productive than if you stop every so often. Taking a 15 minute break every hour is a good idea for most people.

    ____

    If you don't finish your homework during school, think about how much you have left and what else is going on that day, and then budget your time. Most high school students have between 1 and 3 hours of homework a night. If it's a heavy homework day and you've got an assignment in every subject, you'll need to devote more time to homework. It's a good idea to come up with some kind of homework schedule, especially if you are involved in sports or activities or have an after school job.

A. Make a homework schedule.

B. Settle down to do homework.

C. And it helps digest important concepts.

D. Most people's attention spans (跨度) aren't very long.

E. Don't be afraid to ask questions about what's unknown.

F. Once your homework is done, you can check over it if you have extra time.

G. But the more work you can get done in school, the less you'll have to do that night.