Read the following passage and Mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 44 to 50.

The robot revolution isn't a thing of the future - robots are taking over right now and the world of work is never to be the same again.

When having trouble swimming in the sea, you will be glad that Emily is there to rescue you. Emily, not a lifeguard, is a remote-controlled robot that races through the water ten times faster than any human swimmer. Despite not dragging you back to shore, she will keep you afloat until a lifeboat picks you up. Elsewhere, the US Navy is working on Octavia, a robot firefighter that never gives up. It battles through the smoke and flames to extinguish fires that would be very dangerous for human firefighters.

Even the best surgeon's hand sometimes shakes while operating on a patient. Soon though, patients will wake up after surgery knowing that the steadiest of robotic arms will have been operating on them. Meanwhile, in another part of the hospital, a robot nurse, the RP7, will be taking a patient's pulse and temperature then emailing their medical history to a specialist in another country. In the corridor, a fleet of robots will be hard at work day and night collecting dirty sheets, delivering clean ones and distributing food. These robots won't replace humans, but they will allow the human staff to make progress in saving people's lives.

A robot waiter shows you to your table, takes your order and heads for the kitchen where the chef, another robot, cooks your steak. After a delicious main course, another robot provides entertainment until the dessert comes. It may sound like a sci-fi film, but actually this is the Haohai Robot Restaurant in China where all 18 members of staff are robots. The customers don't need to give them a tip and they only work a five-hour shift before taking a two-hour break to recharge their batteries.

The word extinguish in paragraph 2 is closest in meaning to ______.