By far the most common snake in Britain is the adder(奎蛇). In Scotland, in fact, there are no other snakes at all. The adder is also the only British snake with a poisonous bite. It can be found almost anywhere, but prefers sunny hillsides and rough open country, including high ground. In Ireland there are no snakes at all. Most people regard snake bites as a fatal(致命的)misfortune, but not all bites are serious, and very few are fatal. Sometimes attempts at emergency treatment turn out to be more dangerous than the bite itself, with amateurs(外行人)heroically, but mistakenly, trying do-it-yourself surgery(手术)and other unnecessary measures. All snakes have small teeth, so that all snakes can bite, but only the bite of the adder presents any danger. British snakes are shy animals and far more frightened of you than you could possibly be of them. The adder will attack only if it feels threatened, as can happen if you take it by surprise and step on it accidentally, or if you try to catch it or pick it up, which it dislikes intensely. If it hears you coming, it will normally get out of the way as quickly as it can, but adders cannot move very rapidly and may attack before moving if you are very close. The effect of a bite varies considerably. It depends upon several things, one of which is the body-weight of the person bitten. The bigger the person, the less harmful the bite is likely to be, which is why children suffer far more seriously from snake bites than adults. A healthy person will also have better resistance against the poison. Very few people actually die from snake bites in Britain, and though these bites can make some people very ill, there are probably just as many cases of bites having little or no effect, as there are of serious illness. Adders are most likely to be found______.