When we are ill, we call the doctor, and he examines us and diagnoses the illness. When we have a headache, a stomachache, a sore throat, a cold or a pain in some part of the body, we call the doctor. He takes our temperature and our pulse. He examines our heart, our lungs, our stomach or the part where we have a pain and tells us what is the matter with us. He says: “You have a slight temperature”, or “You have the flu”, or “You have heart disease”. The doctor prescribes medicine, and gives us a prescription, which we take to the chemist, who makes the medicine. The doctor says: “Take the medicine twice a day or three times a day, before or aftermeals”. If you follow the doctor’s orders, you get better; if you disobey the doctor you may get worse or even die. If we have a temperature, we must stay in bed and take the medicine prescribed. If we cannot get better at home, we must go to hospital. If we are too ill to walk there, we go in the ambulance. When we have a toothache, we go to the dentist. The dentist examines our teeth. He says: “That tooth has a cavity. I must put in a filling”. If the tooth is too bad, the dentist extracts it.