During the COVID-19 pandemic，many people developed new hobbies at home.However，the 17-year-old Benjamin Choi，a high schooler in Virginia，US，began working on an invention that would quickly go beyond the scale of just a "pandemic project".He set out to design and build an affordable robotic，prosthetic（假 體 的）arm that could be mind-controlled without requiring any brain surgery，reported Smithsonian magazine.
   Choi was inspired by a 60-minute video he'd watched in third grade where researchers implanted tiny sensors into a patient's brain，allowing her to move a robotic arm using her thoughts. "I was really amazed but also alarmed that they require this risky open brain surgery."
   Choi set out to design an improved version himself.With past experience in programming and robotics，he was able to independently design the first version of his robotic arm using his sister's 3 D printer.This initial version worked，using brain wave data and head gestures.The brain wave interpretation algorithm （算法） he had to write from scratch，for which he's now acquired a provisional patent （臨時專利權(quán)），was still to come.
   In October 2020，he received a support in money from polySpectra，a company that produces durable 3 D-printed materials.They helped to produce his arm，moving it out of the prototype（原型） stage and making it working for daily use.
   After over 75 designs，Choi's non-invasive，mind-controlled arm is now made from engineering-grade materials.It operates using the algorithm，which is driven by artificial intelligence that interprets a user's brain waves.The arm remains affordable—it costs under ￥300 （around 2，000 yuan） to make.
   Now，the invention has earned him a spot in the top 40 finalists of one of the oldest and most prestigious science and math competitions for US high school seniors.Choi wants to continue to improve his prosthetic arm in the future.

（1）What inspired Choi to create a mind-controlled arm？

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D

A．A brain surgery he read about in a magazine.
B．A famous science competition.
C．A documentary about tiny sensors.
D．A video he watched before.
（2）What did he do to create the mind-controlled arm？

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C

A．He used a small 3 D printer sponsored by polySpectra.
B．He learned programming and robotics from other experts.
C．He wrote a brain wave interpretation algorithm himself.
D．He and his sister designed the first version of the robotic arm.
（3）What do we know about the latest version of the prosthetic arm？

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C

A．A tiny sensor was implanted into it.
B．Choi wrote a whole new algorithm for it.
C．It is made from engineering-grade materials.
D．It is able to categorize brain wave patterns.
（4）Which of the following words best describe the mind-controlled arm？

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A．Unique but expensive.
B．Creative but unstable.
C．Advanced and complicated.
D．Safe and affordable.