When people are struck by lightening, they fall to the ground as though they were struck b

y a severe blow to the head. After the shock they may remain unconscious, become semiconscious or be conscious but confused and dazed, at least for a time. Flashes of light may continue passing before their eyes, and blindness and deafness may follow. The nervous system may be badly affected, causing paralysis, pain in the limbs and even hemorrhage. There will be burns where the lightening passed through the body, and like all electrical bunts, they are often deep and sever. All persons, especially campers and hunters, should know how to give first aid to someone who has been struck by lightening. Do not be afraid to touch the victim. You wont get a shock. The lightening has already been grounded. Remember that speed is of the greatest importance in severe cases. The first thing to do is to loosen tight clothing about the throat and waist. Then clear the air passages of mucus(黏液)if present, and apply artificial respiration if necessary. Give mouth-to-mouth resuscitation if needed, or give oxygen if available. Many victims thought to be dead have been revived after treatment. Send someone for a doctor as soon as possible, but dont leave the victim alone. If a doctor is not available, take the person to a hospital as soon as the person can be safely moved. Signs of shock are: pale, cold, sticky skin; weak, rapid pulse; shallow, irregular breathing or, in extreme cases, no breathing at all. To treat shock, you must keep the patient lying down with the head lower than the feet and cover him or her with a blanket but watch out for overheating. Giving a stimulating hot tea or coffee will help, but only if the patient is thoroughly conscious. After breathing has been restored and shock is treated, treat the burns. Apply some salve and cover them with a clean cloth or a sterile dressing. If conscious, the patient will be badly frightened, so do all you can to reassure. A little knowledge and a helping hand may save someones life.

The passage mainly talks about______.

A．which metals conduct electricity best

B．where to go in a thunderstorm

C．how to treat someone struck by lightening

D．how to make mouth-to-mouth resuscitation