A、An artificial heart, a battery, a controller, and a transmitter. B、An artificial heart, a battery, a wall outlet, and a transm

Old age is often accompanied by various kinds of illnesses. When he woke up on a July morning in 2001, Robert Tools, 59, could hardly lift his head off his pillow. He had suffered from heart troubles since a decade ago.(20)The 6-foot-3-inch former librarian and administer was too sick for a heart transplant. So he agreed to let two surgeons try something that had never been done before.(21)That afternoon Tools became the first person ever to be implanted with a self-contained artificial heart.(22)Eight days later, Tools left the hospital for the first time to take a stroll through a city park, with his artificial heart pumping blood through his body. The heart is powered by(21)a battery implant that holds a 30-to-40 minute charge. The battery is recharged via a coil attached to an external battery pack good for two hours, which Tools wears on a belt. Or the coil recharger can be plugged directly into a wall outlet.(21)A small controller, about the size of a palm, is also implanted in the chest to regulate blood flow. The tiny controller knows how to adjust to his body’s need for higher or lower blood flow when he stands, sits, walks, or otherwise.(22)But Tools’ mobility is still limited. Most of the time,(21)a transmitter implanted in his chest broadcasts data to a computer in his hospital room so that doctor can continually monitor and fine-tune the blood flow.(22)Tools says living with an artificial heart means adjusting to some strange new sensations. "The biggest thing is getting used to not having a heart beat, except a whirring sound, and that makes me realize that I’m alive because I can hear it without a stethoscope(听诊器)."
20. What do we learn about Robert Tools from the passage?
21. What devices were implanted into Tools’s chest?
22. What’s the result of the treatment?