21、There have been many important developments in medicine．The following are two developments that have been very important in saving lives．

Imagine having an operation and being wide awake．This won’t happen，thanks to something called anesthetic．Anesthetics are given to people during operations so that they fall asleep．Anesthetics cause the muscles to relax and the body to become numb（lose all feeling）so that no pain is felt．This helps the doctors to operate more easily．Anesthetics may be taken in different ways：

●Breathing in a gas

●An injection straight into the bloodstream

●Swallowing a tablet

A local anesthetic numbs only the area where the doctor needs to work．A general anesthetic is when a Patient is put into sleep while the doctor operates Anesthetics were first given in 1844．

Heart disease is one of the biggest killers in the world today Luckily，something can be done about it．Someone who has an unhealthy heart can have a heart transport operation．A heart transplant is when the damaged heart of a patient is taken out and a healthy heart is put in．It is said，though，that the healthy heart has to come from someone who has died Doctor Barard from South Africa was the first person to do a heart transplant operation in 1967．Many successful transplants have been done since then．

It is wonderful what doctors are able to do for us．

（    ）1．With the help of______，patients aren’t able to feel painful during the operations．

A．injections             B．pills                     C．gas                        D．anesthetics

（    ）2．Anesthetics have been used for about______．

A．200                     B．184                     C．165                       D．41

（    ）3．Which does a doctor use to do a heart transplant operation to save lives，a damaged heart or a healthy heart?

A．A damaged heart     B．A healthy heart    C．Both                      D．Neither