题干

如图为静止在竖直墙面上的“爬墙遥控车”,质量为0.03千克,“腹部”有吸盘,当“爬墙遥控车”的真空泵将吸盘内的空气向外抽出时,遥控车能牢牢吸在竖直的墙面上而不会掉落,这是因为遥控车(  )

A:质量小,重力可以忽略不计

B:受到墙面对它向上的摩擦力

C:受到大气对它的压力

D:受到空气对它的浮力

上一题 下一题 0.0难度 选择题 更新时间:2019-05-23 03:50:35

答案(点此获取答案解析)

B

同类题5

阅读理解

    According to findings of a survey by Citi and Seventeen Magazine, nearly four out of five (almost 80 percent) college students work while attending college, with the average work load of 19 hours per week. But should college students work while at college? Many factors should be considered.

    One benefit of working while in college is that it can help build your resume, regardless of whether the job is in your field, according to an article at Scholarships.com. "If you're lucky enough to find a job that closely relates to your major, you could get a leg up on the rest of your class once you graduate, because you'll have more experience in your chosen field," according to the article.

    Perhaps the most compelling reason for working while earning a degree is the money. While it's unlikely to entirely finance your education through a part-time or full-time job, you can still make quite a dent(削减)in the college bill by working.

    But some students prefer not to work while earning a degree so they can focus on getting the best grades. It's true that you'll have more time to stay at school if you don't work, provided you use that time wisely. If you feel like even 10-15 hours a week of work will hurt your grades, then perhaps you should not consider working.

    Working a part-time or full-time job can take away time from social activities, according to a You University TV article. "Trying to balance a job and your college studies, and taking a job can cut down your time to hang out with friends," according to writer Dave Potts.

    In addition to missing out on hanging out with your friends, working during college could prevent you from attending a number of campus events, such as movies on the lawn or football games. While you may be able to land a job that's flexible, it seems unlikely they'll let you choose your own schedule.

    So should students work at college? The decision should be made on a case-by-case basis. Some students can also thrive in school while working, whereas others can't.