ing about a lowering of the general level of intelligence in the population. (7)This argument, does not hold water.(8) For they fail to recognize that in addition to gene, intelligence also depends on an adequate diet, a good education and a decent home environment. (9)And all these things are in danger of being denied as our population is increasing faster than the supply of food, available resources and job opportunities.
(10)If we want to improve the quality of our lives; if we want everyone to be healthy, wealthy and happy; and if we want to see a prosperous, powerful nation in the world, strict birth control is quite essential.

过渡句型

1. It sounds like a good (attractive, palatable) idea (suggestion), but they fail to understand (see, notice)…
2. There is probably an element of truth in the arguments (ideas), but they ignore a more important (basic) fact…
3. Closer examination (analysis), however, suggestions (shows) that this argument (claim, idea) may not be borne out (supported) by the following evidence (facts, examples, statistics).
4. A close (careful) examination (analysis) of these arguments (ideas, suggestions), however, would reveal (suggest, prove) how flimsy (fallacious, groundless) they are.
5. However, logical (sound, forcible)these arguments may be, they don’t make sense (only skim the surface of the problem) when… is viewed the other way (taken into consideration).
6. As opposed to (Contrary to ) the widely (commonly, generally) held idea (belief, view), new studies (facts) challenge (fail to justify) the opinion (view).

叙述理由和分析原因是属于同一类的议论文.所不是后者主要解释某一社会现象或社会问题,而前者则解释作者----我,为什么要干某事或不干某事.
基本结构如下:
PⅠ S1 Topic
    S2 Thesis: My attitude towards it
PⅡ S3 Thesis (more specific)