题目内容：

In an unmanned supermarket,a customer waits to pay.With the use of advanced digital payment technology, including biological recognition and in-depth learning,the man leaves in a minute.There's no cashier in the store.At a large university,students use a hand-scanning machine that authorizes their entry into the gym.Those people are using “smart machines” which identify people by their physical characteristics.These new devices use fingers,hands, faces,eyes and voices.Some machines may even use smells.This new technology,called biometrics,gets information from parts of the body.

In the past,biometric machines were used mainly in government agencies or in prisons.But now that the cost of the technology is lower,these machines are starting to be used everywhere,from border services to schools.

Some people,however,are concerned that these machines will mean the destruction of personal privacy.They worry that the machines will get personal information about them.“I know it seems like these machines are invading our privacy,but actually,biometric machines help to protect it,”says Jay Tarkett,who works at a company that develops the machines.“They can be used instead of passwords on a computer,for example.They can also identify criminals at airports.So,really,they help to promote public safety,and all the information stored is kept confidential by  the machine itself.”

Some people don't like the idea of using fingerprints because they associate them with criminals,and feel like they are being accused of something.In addition,they don't work for some people,such as bricklayers,who wear down their fingerprints.Yet,face recognition does work well because the subject doesn't really have to do anything.To cash a check at a bank,for example,the customer has to do nothing more than look at a machine similar to an automatic teller.If the face matches the picture kept on fie,the customer gets the money with no problems.The need to carry identification with you from place to place,then,would all but cease.

It has been found that the hand scan works well in the college gym.Before this machine was used,students at the college entered the gym using cards similar to credit cards.The problem was that students often lost or forgot their cards.With the hand-scanning machine,however,the problem was solved right away.

But the machines are still new,and there can be problems.For example,voice recognition works on the phone, but it is not precise,and can be tricked.Another constraint（限制）we notice,with machines that use face recognition in particular,is that they can be fooled if people color their hair or gain a lot of weight.However,this particular problem may be solved by a new type of technology that scans a person's iris,the colored part of the eye.It can even identify the person from a few feet away,recognizing a customer as he or she approaches the ATM.

1.What's the author's intention by presenting two examples in Paragraph 1?

A. To stress how smart machines work.

B. To bring in the topic of the passage.

C. To show the popularity of smart machines.

D. To introduce the convenience smart machines offer.

2.Why don't people like using finger-prints while using the machine?

A. They want to keep their mistakes a secret.

B. They don't want to damage their fingers.

C. They are afraid of losing money in the bank.

D. They are afraid of being thought of as criminals.

3.Why are biometric machines starting to be used in many fields?

A. They are not as expensive as they were.

B. They no longer invade people's privacy.

C. People enjoy face and voice recognition.

D. Criminals are often hidden at airports.

4.What is the author's attitude towards the new technology?

A. Worried.    B. Bitter.

C. Optimistic.    D. Satisfied.

5.What is the passage mainly about?

A. An introduction to biometric machines.

B. An advertisement for biometric machines.

C. A brief description of hand scanning machines.

D. An analysis of biometric machines' value in economy.