Diseases of Agricultural Plants

    ants, like animals, are subject to¹ diseases of various kinds. It has been estimated that² some 30,000 different diseases attack our economic plants； forty are known to attack corn, and about as many attack wheat. The results of unchecked plant disease are all too obvious in countries which have marginal food supplies. The problem will soon be more widespread as the population of the world increases at its frightening rate.³ Even in countries which are now amply fed by their agricultural products there could soon be critical food shortages. It is easy to imagine the consequences of some disastrous attack on one of the major crops ； the resulting famines could kill millions of people, and the. resulting hardship on other millions could cause political upheavals disastrous to the order of the world.      

    me plants have relative immunity to a great many diseases，while others have a susceptibility to them⁴. The tolerance of a particular plant changes as the growing conditions change. A blight may be but a local infection easily controlled⁵ ； on the other hand it can attack particular plants in a whole region or nation. An example is the blight which killed virtually every chestnut tree in North America. Another is the famous potato blight inIrelandin the last century. As a result of that, it was estimated that one million people died of starvation⁶ and related ailments.

    ant pathologists have made remarkable strides in identifying the pathogens of the various diseases. Bacteria may invade a plant through an infestation of insect parasites carrying the pathogen. A plant can also be inoculated by man. Other diseases might be caused by fungus which attacks the plant in the form of a mold or smut or rust⁷. Frequently such a primary infection⁸ will weaken the plant so that a secondary infection may result from⁹ its lack of tolerance. The symptoms shown may cause an error in diagnosis¹⁰，so that treatment may be directed toward bacteria which could be the result of a susceptibility caused by a primary virus infection.

词汇：

unchecked / ˌʌnˈtʃekt/adj.未加制止的；未经核对的 

blight/ blaɪt/n. 枯萎病
virtually / ˈvɜ:tʃuəli/adv.实际上

pathologist/ pəˈθɒlədʒɪst/n. 病理学家

pathogen / ˈpæθədʒən/n.病原体

parasite/ "pærəsaɪt/n.寄生虫

inoculate/ɪ"nɒkjʊleɪt/vt.给……接种，给……预防注射
mold/ məʊld/n. 霉病

smut / smʌt/n.黑穗病

rust / rʌst/n.诱病

virus/ "vaɪrəs/n. 病毒
marginal / "mɑ:dʒɪnl/adj.临界的，勉强的

amply / "æmplɪ/adv.充裕地，足够地

critical/ ˈkrɪtɪkl/adj. 严重地，危急的

shortage / ˈʃɔ:tɪdʒ/n.不足
disastrous / dɪˈzɑ:strəs/adj.灾难性的

famine / ˈfæmɪn/n.饥荒

upheaval / ʌpˈhi:vl/n.动乱
immunity/ ɪ"mju:nətɪ/n. 免疫力

susceptibility / səˌseptəˈbɪləti/n.易受感染

注释：

1.be subject to:易受……的，常遭……的；易患……的
2.It has been estimated that:据估计。英语句子的一般顺序是“主语+动词”。但如果把所讨 论的句子改写成 That some 30,000 different diseases attack our economic plants has been estimated.这就很不好。在英语中，信息含量多的成分总是放在句子尾端的位置。这个句 子违背的就是这一条原则。it常称作“引専性it”或“预备性it”，它是形式上的主语，实际上 的主语是that引导的从句。这种结构是无人称语体的一种，除常见于科技文献外，还广泛 使用于新闻报道以及日常生活中，如：It has been reported that another earth satellite has been put into orbit. It is said that she slipped arsenic into her tea.可以看出,谁估计了什么，报道了什么，说了什么都无关紧要，重要的是事实本身。
3.The problem will soon be more widespread as the population of the world increases at its frightening rate, as在句中的意思是“当……的时候”，跟when，before等连词一样,引导的时 间状语从句中的一般现在时形式表示“将来”。句中的frightening是现在分词，作定语。分词 短语作定语时,经常放在所修饰的名词之后。如:The man working in the fields is my brother.
4.... while others have a susceptibility to them. 而其{也的会譯艮敏感。others 在这里替代other plants,而 them 在这里指的是 diseases。
5.A blight may be but a local infection easily controlled:植物枯萎病的传播可能只是地域性的， 因而很容易控制。在英语中but可以表示only,在现代英语中这种用法已不多见。
6.die of starvation:死于饥饿。die of 意为“死于……”。又如：He died of cancer. He died of a stroke. He died of boredom.
7.in the form of a mold or smut or rust:句中的 in the form of 意思是“以……方式”。mold 是美国英语，而英国英语是mould。        、
8.such a primary infection： such a 后接可数名词单数形式，又如：Is there such a book in English? I regret having had such an opinion of you.
9. result from的意思是“……引起的结果，由……引起”;result in的意思是“导致……结果”。 试比较：Inflation results from an excess of demand over supply. The use of such techniques could result in disastrous ecological changes. 前一句的主语表结果，后一句的主语表原因。

10. The symptoms shown may cause an error in diagnosis:表现出的症状有可能造成诊断的失误。 过去分词shown在这里作symptoms的后置定语。

According to this passage, which of the following would a plant disease result in if left unchecked?

A:A world war B:Border conflicts C:Rations of grain and meat D:Social upheavals

下面程序段的输出结果是( )。
public class Test
public static void main (String[] args)
int n=10，result=0；
for (int i=1;i＜＝n;i++) result+=i;
System.out.println("result is"+result)；

A:result is 55 B:result is 45 C:result is 56 D:result is 54

下面程序段：
boolean a=false；
boolean b=true；
boolean c=(a&&b)&&(!b)；
boolean result=(a&b)&(!b)；
执行完后，正确的结果是( )。

A:c=false；result=false B:c=true, result=true C:c=true；result=false D:c=false；result=true

下面程序段： boolean a=false； boolean b=true； boolean c=(a||b)&&(b)； boolean result=(a|b)&(b)； 执行完后，正确的结果是

A:c=false；result=false B:c=true,result=true C:c=true；result=false D:c=false；result=true

下面程序段； boolean a=false； boolean b=true； boolean c=(a||b)&&(b); boolean result=(a|b)&(b); 执行完后，正确的结果是

A:c=false；result=false B:c=true；result=true C:c=true；result=false D:c=false；result=true

下面程序段： boolean a=false; boolean b=true; boolean c=(a&&B) &&(!B) ; boolean result=(a&B) &(!B) ; 执行完后，正确的结果是( )。

A:c=false;result=false B:c=true,result=true C:c=tree;result=false D:c=false;result=trae

下面程序段的输出结果是( )。 public class Test { public static void main (String[] args) { int n=10，result=0； for (int i=1;i＜＝n;i++) result+=i; System.out.println("result is"+result)； } }

A:result is 55 B:result is 45 C:result is 56 D:result is 54