One such atomic clock is so accurate that it will probably lose no more than a second in 3000years．It will be of great importance in fields such as astronomical observation and longrange navigation．The heart of this atomic colock is a cesium atom that vibrates 9.2billion times a second when heated to the temperature of biling water．
An atomic clock that operates with an ammonia molecule may be used to check the accuracy of predictions based on Einstein’s relativity theories，according to which a clock in motion and a clock at rest should keep time differently．Placed in an orbiting satellite moving at a speed of 18000miles an hour，the clock could broadcast its time readings to a ground station，where they would be compared with the readings on a similar model．Whatever differences develop would be checked against the differences predicted．
可望更精确计时的原子钟
科学观测和计算的准确性总是有赖于科学家的计时方法的。正是因为这一点，科学家们对可望实现更精确计时的方法感兴趣。
在探求精确中，科学家们已转向依靠以各种不断振动的原子或分子来提供“滴答声”的原子钟。这种设想是可能实现的，因为每一种原子或分子都有自己特有的振动率。例如，氨中的氮原子每秒钟振动或“滴答”作响240亿次。
一只这样的原子钟将是极其精确的，甚至在3000年后可能还慢不了一秒钟。在天文观测和远程航行等方面这将具有极其重大的意义。这种原子钟的心脏部分是一个铯原子，当它被加热到沸水温度时，每秒可振动92亿次。
根据爱因斯坦的相对论，利用一个氨分子作动力的原子钟，可以用来检验预报的准确性。根据这一理论，一只处在运动中的钟和一只处在静止状态中的钟，其计时情况应不相同。把原子钟放在以每小时1.8万英里的速度沿轨道运行的卫星上，它便能向地面站播回其时间读数，在地面站，这些读数将与类似的一只原子钟上的读数相比较。不管误差有多大，都可按预报的数字校准。
Future World
It’s Friday morning in the year 2025，and you’re running late.You got distracted watching the music video that as playing in the corner of your bathroom mirror while you were brushing your teeth.How will you get to your office at Mega Giga Industries on time？
A quick check of your Internetconnected refrigerator magnet tells you your train which travels at speeds up to 250miles an hour as it electromagnetically hovers above its guide track—is a bit behind schedule，too.So you decide to drive your environmentally—friendly hydrogen fuel cell car instead—or rather，let your car drive you.It’s programmed to know the way，and it will get you there without speeding，getting lost，or crashing.
Settling into your office chair，which changes color to match what you’re wearing，you pick up yesterday morning’s newspaper.Printed on reusable electronic paper，it instantly rewrites itself with today’s headlines.Now it’s time for your big meeting.Uh—oh！You’ve left your handwritten notes at home.No problem.The digital ink pen you used has stored an electronic copy of what you wrote.
Your wristwatch videophone suddenly rings.Your best friend’s face pops up on the organic lightemitting diode screen asking what you’re doing this weekend.Will you slap on your 3D contact lenses and play virtual soccer with the U.S.Olympic team？No，no.Your friend says，so you have to take the new elevator （made of microscopic fibers many times stronger than steel）60000miles into space.
Could this scene really take place in just a couple of decades？The researchers who are currently developing all this stuff think so.These gadgets may be as common in 20years as cell phones and DVD players are today.
未来世界
2025年的一个星期五早上，你眼看就要迟到了。你正在盥洗室里刷牙，却被玻璃镜一角正放着的音乐录像弄得分了心。你怎样才能按时赶到米嘉-技嘉公司上班呢？
赶快查一下电冰箱上的磁贴，那是与互联网链接的。磁贴将告诉你：你所要乘坐的、时速达250英里（相当于400公里）的磁悬浮火车，正好也晚点了。于是，你决定开着环保型的氢动力车去上班，或者更确切地说，让你的车载着你去上班。这种车是经过程序设计的，知道行进方向，它可以载着你安全抵达目的地，不超速，不迷路，也不会出车祸。
你把自己舒舒服服地安顿在办公室的椅子上（这种椅子会自动变色，好与你的衣服颜色相配），拿出一份昨天的晨报。报纸是印在可以重复使用的电子纸上的，它立刻自动换上了今天的新闻标题。好啦，你该参加一个重要会议了。哦，你把手写笔记忘在家里了！没问题。你用过的数字水笔已经储存了一份相关内容的电子文本。
突然，你手表上的可视电话响了。你最要好的朋友出现在有机激光显示屏上，问你这个周末有何打算。想戴上三维隐形眼镜，与美国奥林匹克队进行一场虚拟足球比赛？不，不。你朋友说，那么你们打算乘新型的纳米电梯（用微纤维制成，强度比钢高出许多倍）进入60000英里（相当于96000公里）高度的太空遨游。
再过二三十年，这一切真的会发生吗？那些目前正在开发这些东西的研究人员对此深信不疑。20年后，这些小玩意儿就会像今天的手机和DVD机一样随处可见。
The Wonderful Structureof a Microcomputer
In Chinese，a computer is popularly known as an “electrical brain”，for the working process of a computer is similar to a human brain very much.In appearance，a microcomputer has three simple and apparent parts：the main frame，the keyboard and the monitor.In other words，if you own these parts，you would exactly have a computer.A computer system is composed of software and hardware in the light of its working mode.If we compare the hardware to a human body，then，the software would be soul.
Just as a driver can’t drive a car without driving skills or the car itself，you can’t control a computer without controlling techniques or the computer itself.The controlling techniques are called software，while computers themselves and related devices are called hardware.
The work of a computer is just making full use of various resources by software set in the computer，and directing the hardware to realize marvelous omnipotent functions.
Primary Components of a Microcomputer