into play; in the last resort the snake attacks. This pattern vanes with the circumstances;some stages may be omitted or combined unpredictably whilst all some notoriously irasciblespecies may dispense with all the preliminaries and attack almost at once. though seldom ornever without some provocation.

　　Amongst the factors that increase aggressiveness are hunger, the mating season and surprise,with the last mentioned the commonest; when hunting for food or for mate. activity and theaggressive instinct are both at their peak. Owing to their poor sense of hearing snakes arevery liable to be, quite literally, caught napping and a similar situation arises during theirperiods of temporary blindness just before sloughing (蛻皮)begins. By far the greatestnumber of snake-bit accidents result from the unwitting disturbance of resting snakes. and thishazard is much increased with species that are well disguised and whose natural instinct is totrust to this concealment as their principal defense. As well as differences in aggressivenessbetween individuals of the same species according to the circumstances and conditions, thereare also notable differences between species, even closely allied species; and the reports ofthose who have been attacked may understandably be lacking in objectivity. So it isimpossible to forecast. even in outline, how any encounter will develop.

　　The Hamadryad, for example, is usually credited with being amongst the most aggressive ofsnakes. and there are many accounts of unprovoked attacks, yet on one occasion fourteenmen and seven dogs passed and returned within two yards from a nest and no snake was seenalthough the female. which guards the nest, could not have been far away.

　　蛇的品種繁多。有各式各樣的天敵，無疑，它們有數之不盡的防御方式和武器。但是，它們有一種共同的行為模式。[1]在遇到可疑的敵人時，它們的第一反應就是設法避開對方的監視;如果這個不成功的話，第二個方法就是逃到一個對方難以接近的安全之地，但是，如果無處可躲或者陷入包圍，它們就會擺出各種恐嚇的姿勢，向對方發出警告;如果以上所有的方法都不奏效，蛇就會向敵人發起攻擊。[2J這種模式會隨著環境改變;它們不一定逐一完成以上四個步驟，也可能毫無預警地把某些步驟結合在一起;而所有那些臭名昭著的殘暴的蛇種，可能一開始就對敵人發起攻擊，而摒棄所有其他的步驟，但是它們這樣做通常是因為受到了挑釁。

　　[3]增加蛇的攻擊性的因素有：饑餓、交配季節，還有最常見的——受到驚嚇;在覓食和尋找交配對象的時候，蛇的行為和攻擊的本能都達到最高峰。因為蛇的聽覺很差，所以，在它們打盹的時候，通常最容易被捕獲，蛇在開始蛻皮的時候會暫時失明，同樣這時蛇也最容易被捕獲。到目前為止，在被蛇咬到的事件中，大多數是因為人們無意中打攪了正在休息的蛇，而碰上那些偽裝性很強的蛇(它們主要的防衛措施就是本能上依靠偽裝隱藏自己)，人們受到攻擊的危險就更大了。[4]因為環境條件的差異，所以在同一品種的蛇中，每條蛇的攻擊性不一樣，除此之外，不同的蛇種，即使近親品種，也有明顯的差別;于是，那些曾被蛇攻擊過的人，他們的報告很可能缺乏客觀性，這也是可以理解的。[5]因此，每一次當人蛇遭遇時，事情將如何發展，都無法預測，甚至概括性的預測也是不可能的。

　　[5]例如，人們常常認為眼鏡王蛇是最具攻擊性的蛇，它通常無緣無故對人發起攻擊;然而，有一次, 14個人帶著七條狗在距離蛇窩兩碼的地方來回走過，卻一直沒有看到蛇的蹤影，但是，看守蛇窩的雌蛇必然就在近處。

　　1.When a snake meets a potential enemy, itsprimary device is______________.

　　A) avoiding any observation

　　B) Finding a safe shelter

　　C) giving a warning threat

　　D) starting a quick attack

　　2.The underlined phrase "dispense with all the preliminaries" in Paragraph I mostprobably means________________.

　　A) the snakes combine all the previous three steps

　　B) the snakes give up all the previous three steps

　　C) che snakes follow all the previous steps one by one

　　D) the snakes reverse the order of all the previous steps

　　3.A snake is most aggressive when_______________.

　　A) it meets a possible enemy

　　B) it is caught when it is sleeping or sloughing

　　C) it is disturbed unknowingly

　　D) it seeks a partner in che mating season

　　4.It is difficult to predict what would happen when a snake meets a manbecause____________.

　　A) no one bas ever clearly known how he himself was bit

　　B) man tends to be subjective when he describes his encounter with a snake

　　C) the aggressiveness of the snakes differs according to diverse situations

　　D) a snake does not begin co attack without provocation

　　5. The author uses the example in the last paragraph m support his ideathat___________.

　　A) snakes do not begin the aggressive act if it is not disturbed

　　B) some snakes are more aggressive and more ready to attack

　　C) it is hard to forecast whether and how snakes would attack

　　D) snakes often conceal themselves as their principal defense