题干

下列关于惯性的说法中正确的是(   )

A:在太空中飞行的宇宙飞船内物体没有惯性

B:物体只有在突然运动或突然静止时才有惯性

C:物体质量越大,惯性越大

D:物体运动速度越大,惯性越大

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答案(点此获取答案解析)

C

同类题1

阅读下面文章,完成下列各题。

有一种精神叫专一

周云龙

       ①“右手画圆,左手画方,不能两成。”《韩非子》中的这一名句,现代科学给出了解释,即大脑两半球的连接机制无法同时向左右手分别传达“画圆”和“画方”的命令。无数事实也表明,用心专一,事业方可成功;反之,则一事无成。

       ②屠呦呦就是用心专一的典型。55年里,除了参加为期两年半的“西医离职学习中医班”,她几乎无长时间离开过东直门附近的那座小楼;为了不影响研究,她把孩子交给母亲抚养,即便得了中毒性肝炎也还在充满乙醚气味的环境下工作;从 2000多种中草药制剂中,历经 380 多次鼠疟筛选,经历了 190次失败,最终提取了关乎上百万生命的青蒿素。科学界巨星“三钱”之一的钱伟长,不管做什么研究,都非常专一。他不驰于空想,不骛于虚声,而惟以求真的态度作踏实的研究。终在应用数学、弹性力学、中文信息学等领域获得重要成就,被人称为“万能科学家”。屠呦呦、钱伟长的事业轨迹似乎在提醒人们:获得成功的途径,唯有专一。

       ③反之,不务正业,不仅不会成功,反而贻害无穷。明熹宗朱由校不专一治国,痴迷木匠,虽技艺堪比巧匠,却误国害民。现实中亦有不少这样的人。有一位著名的骨科专家,担任医院院长之后,便心有旁骛,不专一于“正业”,热衷搞房地产开发,虽然医院规模不断扩大、地盘不断拓展,但诊断、医疗的服务质量却不断下降,最终导致医疗事故频发,病人及家属怨声载道。许多教训表明,在其位不专一其政,却将精力用于怎么升官、怎么发财、怎么享乐,终必误人误己。

       ④荀子云:“蚓无爪牙之利,筋骨之强,上食埃土,下饮黄泉,用心一也。蟹六跪而二螯,非蛇鳝之穴无可寄托者,用心躁也。”许多禀赋很好的人,不屑为“蚓”,向往威武之“蟹”,在最青春的年华,将大量的时间、心力耗费在名、权、利的追逐上。事业偏轨,难有大成,殊为憾事。寄心于旁骛,或有短暂的满足,却终会步入歧途。

       ⑤在浮华喧嚣的环境下,专一往往体现为一种定力、自制力、免疫力,乃至挫折承受力。有专一精神打底,在人生和事业的路途上,至少能拥有内心真正的平静,享受实现人生价值的快乐,即便仍然可能面临失败。

(选自《人民日报》2015年 11月 20日 04版  有删改)

同类题2

阅读下列短文, 根据短文中的信息完成文后表格, 每空一词。

      WARNING(警告): Holding a cell phone against your ear or putting it in your pocket may be bad for your health. This sentence is a warning that you’d better not put it close to you when a new phone is bought. Apple company, for example, doesn't want iPhones to come closer to you than 1.5 centimeters; Research In Motion, BlackBerry's producer, recommends 2.5 centimeters.

      If cell phone use can cause health problems, the result will be very serious. Americans spend 2.26 trillion minutes chatting on cell phones every year, which brings $109 billion for the wireless businessmen.

      Devra Davis, an epidemiologist(皮肤病专家)who has worked for the University of Pittsburgh, has published a book about mobile phone radiation(辐射)"Disconnect." Davis studies how often brain cancer happens during different age groups. As a result of mobile phone radiation, she finds that a big increase(增长)in brain cancer in the 20-to-29 age group and a drop for the older people.

      Children are more easily hurt by radiation than grown-ups, Ms. Davis and other scientists point out. But no studies have yet been finished on cell phone radiation and children, she says.

      Henry Lai, a research professor, began lab radiation studies in 1980 and found that mice exposed to(暴露在) radiofrequency(电波频率)radiation had destroyed DNA in their brains.

      Ms. Davis recommends using wired earphones(有线耳机)or the phone's speaker. Children should send text messages rather than call, she said, and pregnant women should keep phones away from their bodies.

It's ____to your health to use cell phones

____from different companies.

● Apple company ____ using cell phones at least 1.5 centimeters.

● Motion, BlackBerry's producer ____ 2.5 centimeters.

The____of research from different areas

● Devra Davis pointed out in the book "Disconnect" that people in the 20-to-29 age are more likely to have brain cancer than older people ____of mobile phone radiation.

● Ms. Davis and other scientists studied that Children are ____ to be hurt by radiation than adults.

● Henry Lai found that ____exposed to(暴露在) radiofrequency(电波频率) radiation had destroyed DNA in their brains.

Ms Davis's____on how to use the cell phone safely

●Children should send text messages ____of call.

 Pregnant women should keep phones away from their bodies.