题目内容：

    In a world where nearly 6 million fingerprint records of government employees are stolen in one computer hack, and where millions of people are victims of identity theft every year, the next step in cyber security may well be mapping your brain.

Researchers at Binghamton University, State University of New York arc working on a biometric （生物特征 识别的）system that records how your brain reacts to certain images. With a little more polishing, the scientists' brainchild could become the way you get into a safe deposit box, your office or past scanners at the airport. It could replace the password for your online banking, your email or your social media accounts.

They started their project by measuring the brain waves of 30 subjects. The subjects were fitted with a cap that had 30 electrodes （电极）attached to it, and then shown various images and symbols — celebrity faces, words, pictures of food --- on a computer screen in 200-millisecond bursts. The brain\ reaction was recorded.

The idea is that every time a person needs to use a “password", he or she goes through the same procedure, and the results are matched with their first-time reaction. If the "brainprint" is compromised --- like what happened with the fingerprint records --- then the system is merely reset by running another set of images and collecting a different set of brain waves。. "Even if that was stolen, you could just cancel it and record one to something else", says professor Laszlo.

Laszlo and her team have shown that their system can be 100 percent accurate. So one of the more difficult parts of making the system practical already has been overcome. Now, they're spending much time recording accurate brainprints with as few as three electrodes, which could make recording in the future as easy as wearing a pair of special glasses. They're also working with cheaper materials and different methods to see if they can bring the cost down.

1.What does the underlined word "brainchild" in paragraph 2 refer to?

A.The brain function. B.The fingerprint record.

C.The online password. D.The biometric system.

2.Why were the images and symbols shown to the subjects?

A.To check the brain's reaction.

B.To create their brainprints.

C.To match brainprints with pictures.

D.To connect brain waves to electrodes.

3.What will happen when a brainprint fails?

A.A new one will be set

B.A spare one will be made ready beforehand.

C.The users' identity will be stolen.

D.The fingerprint record will replace it.

4.What are the researchers doing with the program now?

A.Improving its accuracy.

B.Recording more brainprints.

C.Making it user-friendly.

D.Increasing the number of electrodes.