20．The adder is the only poisonous snake native to Britain．Adders have the most highly developed poison injecting mechanism of all snakes，but they are not aggressive animals．Adders will only use their poison as a last means of defence，usually if caught or trodden on．No one has died from adder bites in Britain for over 20 years．By faar the most common smake in Britain is the adder．In Scotland，in fact，there are no other snakes at all．The adder is also the only British sanke with a poisonous bite．It can be found almost anywhere，but prefers sunny hillsides and rough open country，including high gournd．In Ireland there are no snakes at all．
Most people regard snake bites as a fatal 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 heroically，but mistakenly，trying do-it-yourself surgery and other unnecessary measures．
All snakes have small teeth，so it follows tha tall snakes can bite，but only te bite of the adder presents any danger．British snakes are shy animals and are fare 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 severa things，one of which is the boidy-wight 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 in Britain，and thought these bites can make soime pepe very ill，thre are probaably just as many cases of bites having little or no effect，as there are of serious illess．
28．What does the underlined phrase"trodden on"probably mean？C
A．Found out B．Heard from C．Stepped on D．Robbed of．
29．Where are adders to be found？B
A．In fertile fields in Scotland
B．On wild land throughout Britain．
C．In many parts of Britain and Ireland
D．Everywhere in Britian except Scotland
30．What should you do if you are with someone who is bitten by an adder？C
A．Catch the biting adder at onece
B．Don't worry about the bitten person．
C．Don't try to treat the bite by yourself
D．Operate on the person as soon as possible．
31．What's the best title of the passage？B
A．Poisonous Snakes
B．Adders in Britain
C．Take Care oif Sake Bites
D．Protec Endangered Adders．
分析 文章主要介紹了 adders 這種蛇，包括它的分布、習(xí)性、以及被蛇咬時應(yīng)注意的事項等．
解答 CBC B
28：C 推斷題．由劃線詞所在句"Adders will only use their poison as a last means of defence，usually if caught or trodden on．"可知，adders 不到萬不得已不會使用毒液，這種萬不得已的情況通常是被捉到或被 trodden on 的時候．A項"找出"，B項"聽說"，C項"踩上"，D項"搶劫"，只有C項代入文章能講得通，即 adders 在被捉到或被踩到的時候才會使用毒液．其他三項均不符合語境，故正確答案為C．
29 B 細(xì)節(jié)題．由第一段倒數(shù)第二句"It can be found almost anywhere，but prefers sunny hillsides and rough open country，including high ground．"可知，adders 幾乎在任何地方都能被找到，尤其喜歡陽光充足的山坡和貧瘠廣袤的鄉(xiāng)村，包括高地．即在 Britain 的野地里可以找到 adders，所以B項正確．A項，由第一段倒數(shù)第二句"…prefers sunny hillsides and rough open country …"可知，adders 喜歡貧瘠的地方而非肥沃的地方，所以A項錯誤．C項，由第一段最后一句"In Ireland there are no snakes at all．"可知C項錯誤．D項，由第一段倒數(shù)第四句"Scotland，in fact，there are no other snakes at all．"可知，Scotland 只有 adders 這一種蛇類，所以D項錯誤．故正確答案為B．
30：C 細(xì)節(jié)題．由第二段第二句"Sometimes attempts at emergency treatment turn out to be more dangerous than the bite itself，with amateurs heroically，but mistakenly，trying do-it-yourself surgery and other unnecessary measures．"可知，遇到有人被蛇咬，慌忙地處理是很危險的，也千萬不要試著自己處理，故正確答案為C．
31：B 主旨題．文章主要介紹了 adders 這種蛇，包括它的分布、習(xí)性、以及被蛇咬時應(yīng)注意的事項等．a(chǎn)dders 為本文關(guān)鍵詞，貫穿整篇文章，所以B項正確．A項，毒蛇有很多種，本文只介紹 adders 這一種，所以A項錯誤．C項，處理蛇咬傷口，偏離文章主旨，所以C項錯誤．D項，保護(hù)瀕危蛇類，偏離文章主旨，所以D項錯誤．故正確答案為B．
點評 考察學(xué)生的細(xì)節(jié)理解和推理判斷能力，做細(xì)節(jié)理解題時一定要找到文章中的原句，和題干進(jìn)行比較，再做出正確的選擇．在做推理判斷題不要以個人的主觀想象代替文章的事實，要根據(jù)文章事實進(jìn)行合乎邏輯的推理判斷．
