A、How to safeguard the computer network. B、How to steal top secret files from a military base. C、How to make modern devices broa

Imagine hackers stealing top secret files from a military base. What if they don’t need the Internet to pull data out of the facility’s computers? Instead, they can just infect an office printer and—with software alone— turn it into a radio. This sounds like sci-fi, but it’s now possible.(9)Security researchers at a Manhattan startup have discovered how to make any modern device—printer, washing machine, air conditioner— broadcast invisible, inaudible signals for miles. That’s a game changer and a huge step forward for hackers.
    The rapidly expanding $77 billion cybersecurity industry is all about guarding computer networks. Companies and governments buy products to stay protected. But they keep running out of effective defensive options. That’s where Ang Cui and his team of bright researchers come in. They found a way to sneak data out of a computer network without setting off any alarms.(10)It’s groundbreaking research, because it also hints at the ability to steal data from computers that aren’t even connected to the Internet, like those at nuclear facilities.
    Last week, the team at Red Balloon Security demonstrated how it works to several news reporters. They infected a Pantum laser printer and toyed with its circuits, making it do something it was never meant to. By quickly switching a chip’s energy output back and forth, the printer emits electromagnetic radiation. The Red Balloon team calls it a "funtenna. "(11)In fact, one of the only ways to detect this highly advanced tactic is by walking around with an AM radio. If you get near a device and the radio static is interrupted by loud beeping, it’s secretly transmitting radio signals.
Questions 9 to 11 are based on the passage you have just heard.
9. What did the security researchers at a Manhattan startup discover?
10. Why is the new hacking tactic groundbreaking?
11. How to prevent the highly advanced tactic stealing data from computers?