阅读说明文《黑匣子》，完成后面的题。
                                                                                               黑匣子
      马航MH-370航班失去联系很多天了，各国救援船只现在都在客机可能坠落的海域进行搜索，但马航波音777客机仍杳无音讯。马航航班失联事件，再次成为一个“史无前例的”事件，这一事件表明全球航空业的数据通信、数据备份实在太落伍。业者建议，黑匣子的数据，应该实时传回地面，这样无需在出现事故之后投入巨大人力物力进行寻找。
      所谓黑匣子，就是一种飞行数据记录仪。黑匣子的外壳坚实，为长方体，约等于四、五块砖头垒在一起一般大。黑匣子被漆成明亮的桔红色，这种明亮显眼的颜色，以及记录仪外部的反射条件，都使得事故调查员们可以在飞机失事后很快地找到记录仪，特别是当飞机坠落在水上时。为了承受飞机坠毁时的猛烈撞击和高温烈焰，黑匣子的外壳具有很厚的钢板和许多层耐热防冲击保护材料。根据欧洲的标准，黑匣子必须能够抵受2．25吨的撞击力，在1100℃高温下10小时仍不会受损。即便飞机已完全损坏，黑匣子里的记录数据也能完好保存。
    “黑匣子”是一位墨尔本工程师在1958年发明的。1908年，美国发生了第一起军用飞机事故。此后，随着飞行事故不断发生，需要有一种追忆事故发生过程原因的仪器。二战期间，飞行记录装备仪器在军用飞机上应用，后来又用到民航飞机上。飞行记录仪之所以被称为“黑匣子”可追溯到1954年，当时飞机内所有的电子仪器都是放置在大小、形状都统一的黑色方盒里。
      大多数的飞机上安装的黑匣子有两种。一是称为飞机数据记录器的黑匣子，专门记录飞行中的各种数据，如飞行的时间、速度、高度、飞机舵面的偏度、发动机的转速、温度等，共有30多种数据，并可累计记录25小时。起飞前，只要打开黑匣子的开关，飞行时上述的种种数据都将收入黑匣子内。一旦出现空难，整个事故过程中的飞行参数就能从黑匣子中找到，人们便可知道飞机失事的原因。另一种称为飞行员语言记录器的黑匣子，就像录音机一样，它通过安放在驾驶舱及座舱内的扬声器，录下飞行员与飞行员之间以及座舱内乘客、劫机者与空中小姐的讲话声，它记录的时间约为2个小时，录完后，会自动倒带从头录起，若发生空难，之前的两个小时会被完整保留，并持续发出讯号，直到断电为止。

一个与球心距离为1的平面截球所得的圆面面积为$\mathrm{\pi }$，则球的表面积为(      )

—I swam in that river .

    As self — driving cars come closer to being common on American roads, much of the rhetoric (说辞) promoting them has to do with safety. About 40,000 people die on U. S. roads every year, and driver errors are linked to more than 90 percent of crashes. But many of the biggest advocates of autonomous vehicles aren't car companies looking to improve the safety of their existing products. Huge backing for self - driving technologies is coming from Silicon Valley giants like Google and Apple.

    Those of us who have studied the relationship between technology and society tend to look more carefully at the motivations behind any technological push. In this case, it's clear that in addition to addressing safety concerns, Silicon Valley firms have a strong incentive (动机) to create a new venue for increasing the use of their digital devices. Every minute people spend on their mobile phones provides data - and often money - to tech companies.

    At present, digital devices and driving are in conflict: There are serious, often fatal, consequences when drivers use smartphones to talk or to text. Regulators and safety advocates look to resolve dial conflict by banning phone use while driving - as has happened in virtually every state. But the tech companies are taking a different approach. The obvious answer for Silicon Valley is creating an antomobile in which continuous cellphone use no longer poses a threat to anyone.

    In recent years, the amount of time adults spend on their mobile devices has grown rapidly. At the moment, it's around four hours a day for the average adult in the U. S. However, that rapid growth is likely to slow down as people run out of time that ' s available for them to use their devices. Unless, of course, there's a new block of time that suddenly opens up. The average American now spends about 48 minutes in a car every day, a sizable opportunity for increased cellphone use.

    So as the public conversation around autonomous cars highlights the safety advantages, don't forget the tech industry ' s powerful desire for more profits, which goes well beyond simply saving us from ourselves.