Thomas Malthus published his "Essay on the Principle of Population" almost 200 years ago. Ever since then,

　　forecasters have being warning that worldwide famine was S1

　　just around the next corner. The fast-growing population's

　　demand for food, they warned, would soon exceed their S2

　　supply, leading to widespread food shortages and starvation.

　　But in reality, the world's total grain harvest has risen steadily over the years. Except for relative isolated trouble S3

　　spots like present-day Somalia, and occasional years of

　　good harvests, the world's food crisis has remained just S4

　　around the corner. Most experts believe this can continue

　　even as if the population doubles by the mid-21st century, S5

　　although feeding 10 billion people will not be easy for

　　politics, economic and environmental reasons. Optimists S6

　　point to concrete examples of continued improvements

　　in yield. In Africa, by instance, improved seed, more S7

　　fertilizer and advanced growing practices have more than

　　double corn and wheat yields in an experiment. S8

　　Eleswhere, rice experts in the Philippines are producing a plant with few S9

　　stems and more seeds. There is no guarantee that plant

　　breeders can continue to develop new, higher-yielding

　　crop, but most researchers see their success to date as S10

　　reason for hope.

　　答案及解析:

　　S1. 应把being改成been。本题考查的是现在完成进行时。现在完成进行时由has ( have) + been + 动词的现在分词构成。如：She has been ringing you up all morning. ( 她给你打了一上午电话。)

　　S2. 应把their改成its。本题犯了名词与代词指代不一致的错误。因为动词exceed后面指代的是前文的food。

　　S3. 应把relative改成relatively。本题把形容词错用为了副词。relative是形容词，改为副词relatively后修饰isolated，意思是"相对地"。

　　S4. 应把good改成bad。本题从语法角度来讲没有错误，但却不符合上下文的意思。

　　S5. 应把as去掉。因为even if 是一个固定短语，意思是"即使……也"。很多学生把even as if 改成了even though，尽管两者意思和用法都很相似，但改动两个词是题目所不允许的，这点希望同学们注意。

　　S6. 应把politics改成political。通过分析上下文可以发现，本题考查的是形容词的平行结构用法，平行结构错误是六级考试改错题中经常出现的，其要点在于句子中出现由and，but，as well as 等连接的并列成分时，这些成分须在形态上保持一致，这样句子的结构才能平衡。

　　S7. 应把by 改成 for。本题较简单，因为for instance (或 for example )是固定搭配。类似的搭配还有：by chance 意外地、偶然地；by accident意外地、偶然地；at random 随便地、任意地； at a loss不知所措；in person 亲自；in practice 事实上、实际上；in general 大体上、一般来说；on sale 出售、上市；out of control 失去控制。

　　S8. 应把double改成doubled。本题的错误是把形容词误用为过去分词，double一词有多种词性，作动词的意思是"使……多出一倍、变成两倍、增加一倍"，根据上下文，这里要用动词的过去分词形式才符合题意。

　　S9. 应把few 改成fewer。本题考查的是形容词的比较级用法。为什么要用比较级？根据上下文的平行结构便明白了。few表示的意思是"很少、几乎没有"，它的比较级是fewer。做改错时，要特别注意句子里有无把-er和more并用的情况，如more longer，more happier，more cleverer等均是错误的。

　　S10. 应把crop改成crops或plants。本题是名词单复数的误用。crop是可数名词，根据上下文可知应该用它的复数形式crops或用它的同类词plants来代替。解此类题时一定要弄清楚句子的含义以及上下文的逻辑关系。

　　(文/吴彬；英语辅导报大学二年级版 03～04学年第39期； 版权归英语辅导报社所有，独家网络合作伙伴新浪教育，未经许可，不得以任何形式进行转载。)