完形填空

    Workers aren't allowed to go into a big underground computer center until they step up to a machine that takes a quick picture of the tiny blood vessels (血管) inside their eyes.

    If the machine can't 1 the picture with images in its computer, the worker is stopped by security guards (保安员).

    Each person has his own way of blood vessels in his or her2.And unlike a key, the way can't be3.Old-fashioned keys and locks may soon be things of the past.High-tech security devices (安全装置) are being fixed at military (军事的) bases, computer centers and banks.Companies that 4 the machines say they'll someday be used in people's homes and cars.

    Already, a Japanese company has fixed ways that recognize (识别) people's fingerprints in 360 new homes.The machines open the doors only for the 5of the houses.The new security ways are selling well because thieves and robbers are getting better at breaking into buildings and computers that are 6 by keys and locks.Since nobody can steal or copy a fingerprint, or one's eyes, the new machines are 7.

    Other new machines recognize one's voice.Two American companies use 8 machines to keep an eye on their computers.Inexpensive voice-recognition machines may someday take the place of locks on cars.The doors would open only for the owners.The machines would 9 the owners as little as $270.Although the up-to-date machines are amazing, scientists must still solve a serious problem.How will a boy borrow his dad's car without borrowing his dad's 10?

典典同学学完统计知识后，随机调查了她家所在辖区若干名居民的年龄，将调查数据绘制成如下扇形和条形统计图：

请根据以上不完整的统计图提供的信息，解答下列问题：

能通过下列现象确认溶液中有NH₄⁺存在的是（　　）

若$f\left(x\right)=x^3+3a{x}^2+3\left(a+2\right)x+1$有极大值和极小值，则a的取值范围是 （   ）

中华民族是一个饱经灾难的民族，灾难使中华民族更加坚强、团结。四川汶川8．0级特大地震将全中国十三亿民众凝聚起来。将全世界炎黄子孙团结起来。汶川大地震改变了许多人的思维习惯和生活习惯。生命显得如此脆弱，大灾无情人有爱，人们为支持地震灾区表现出了无比的热情和爱心。无数人为支援灾区而宁愿牺牲个人利益，这说明
①维护国家利益，就要牺牲个人利益，甚至是个人生命
②在社会主义建设事业中，必须坚持集体主义价值取向
③价值观对人们认识和改造世界具有巨大的促进作用
④集体利益与个人利益相比，处于更为根本的地位