(一)原因題型

　　原因通常成為考點(diǎn)，它的主要出現(xiàn)方式如下。

　　1.段落(含首段)第一句如果表達(dá)一種因果關(guān)系，通常為考點(diǎn)。

　　2.文章中細(xì)節(jié)性的因果關(guān)系——通常由一些表示因果關(guān)系的詞匯手段表達(dá)。

　　(1)表示因果關(guān)系的名詞：basis(根據(jù))，result，consequence，reason;

　　(2)表示因果關(guān)系的動(dòng)詞：result in(結(jié)果)，result from(由于，由……)，follow from(……結(jié)果)，base…on…(以……為基礎(chǔ))，be due to(由于);

　　(3)表示因果關(guān)系的連詞或介詞：because，since，for，as，therefore，so，thus， why，with;

　　(4)表示因果關(guān)系的副詞：as a result，consequently等。

　　(二)條件題型

　　條件關(guān)系通常也是考點(diǎn)，它的主要出現(xiàn)方式如下。

　　1.以when、if、as等連詞引導(dǎo)的條件從句。

　　2.文章中細(xì)節(jié)性的條件關(guān)系——通常由一些表示條件關(guān)系的詞匯手段表達(dá)：如 depend upon(取決于)，determine(決定)等。

　　例1

　　Where do pesticides(殺蟲(chóng)劑)fit into the picture of environmental disease? We have seen that they now pollute soil, water, and food, that they have the power to make our streams fishless and our gardens and woodlands silent and birdless. Man, however much he may like to pretend the contrary, is part of nature. Can he escape a pollution that is now so thoroughly distributed throughout our world? We know that even single exposures to these chemicals, if the amount is large enough, can cause ex-tremely severe poisoning. But this is not the major problem. The sudden illness or death of farmers, farm workers, and others exposes to sufficient quantities of pesti-cides is very sad and should not occur. For the population as a whole, we must be more concerned with the delayed effects of absorbing small amounts of the pesticides that invisibly pollute our world.

　　Responsible public health officials have pointed out that the biological effects of chemicals are cumulative(積累的)over long periods of time, and that the danger to the individual may depend on the sum of the exposures received throughout his life-time. For these very reasons the danger is easily ignored. It is human nature to shake off what may seem to us a threat of future disaster. "Men are naturally mo.st impressed by diseases which have obvious signs,"says a wise physician, Dr. Rene Dubos, "yet some of their worst enemies slowly approach them unnoticed. "

　　People tend to ignore the delayed effects of exposure to chemicals because

　　A. limited exposure to them does little harm to people's health

　　B. the present is more important for them than the future

　　C. the danger does not become apparent immediately

　　D. humans are capable of withstanding small amounts of poisoning

　　這道題考點(diǎn)涉及原因。如果閱讀時(shí)圈劃了有關(guān)因果關(guān)系提示詞，這道題就比較容易做了。因果關(guān)系提示詞在第二段第二句：For these very reasons the danger is easily ignored.由此可知本段的前部為答案所在：化學(xué)制品的生物作用是長(zhǎng)期積累的結(jié)果;化學(xué)制品對(duì)人危害的大小取決于人一生中接收的劑量的多少。C項(xiàng)：“化學(xué)制品的危害沒(méi)有立即顯現(xiàn)出來(lái)”表達(dá)的正是這個(gè)意思，所以是正確答案。

　　例2

　　It is likely that the dispute regarding flats versus(對(duì)，對(duì)抗)individual houses will continue to rage on for a long time as far as Britain is concerned. And it is unfortunate that there should be hot feelings on both sides whenever this subject is raised. Those who oppose the building of flats base their case primarily on the assumption(設(shè)想)that everyone prefers an individual home and garden and on the high cost per unit of accommodation. The latter ignores the higher cost of providing full services to a scat- tered community and the cost in both money and time of the journeys to work for the suburban resident.

　　Some people oppose the building of flats because

　　A. the living expenses for each individual family are higher

　　B. it involves higher cost compared with the building of houses

　　C. they believe people like to live in houses with gardens

　　D. the disposal of rubbish remains a problem for those living in flats

　　這道題考點(diǎn)同樣涉及原因。根據(jù)題干中的關(guān)鍵詞組0ppose the building of flats定位到含有原因表達(dá)法(base…on，意為“以……為根據(jù)”)的相關(guān)句：Those who oppose the building of flats base their case primarily on the assumption(設(shè)想)that everyone prefers an individual home and garden and on the high cost per unit of accommodation.反對(duì)建公寓的人最主要的根據(jù)是，人們都喜歡獨(dú)居于帶花園的住房中，由此可知C項(xiàng)為正確答案。

　　例3

　　Even plants can run a fever, especially when they're under attack by insects or disease. But unlike humans, plants can have their temperature taken from 3,000 feet away -- straight up. A decade ago, adapting the infrared(紅外線)scanning technolo-gy developed for military purposes and other satellites, physicist Stephen Paley came up with a quick way to take the temperature of crops to determine which ones are un-der stress. The goal was to let farmers precisely target pesticide(殺蟲(chóng)劑)spraying rather than rain poison on a whole field, which invariably includes plants that don't have pest(害蟲(chóng))problems.

　　Even better, Paley's Remote Scanning Services Company could detect crop prob-lems before they became visible to the eye. Mounted on a plane flown at 3,000 feet at night, an infrared scanner measured the heat emitted by crops. The data were trans- formed into a color-coded map showing where plants were running "fevers". Farmers could then spot-spray, using 50 to 70 percent less pesticide than they otherwise would.

　　The bad news is that Paley's company closed down in 1984, after only three years. Farmers resisted the new technology and long-term backers were hard to find.

　　But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to get back into operation. Agriculture experts have no doubt the technology works. "This technique can be used on 75 percent of agricultural land in the United States, " says George Oerther of Texas A&M. Ray Jackson, who re- cently retired from the Department of Agriculture, thinks remote infrared crop scan- ning could be adopted by the end of the decade. But only if Paley finds the financial backing which he failed to obtain 10 years ago.

　　Infrared scanning technology may be brought back into operation because of

　　A. the desire of farmers to improve the quality of their produce

　　B. growing concern about the excessive use of pesticides on crops

　　C. the forceful promotion by the Department of Agriculture

　　D. full support from agriculture experts

　　根據(jù)題干中的關(guān)鍵詞組“brought back into operation”找到原文相關(guān)句：But with the renewed concern about pesticides on produce, and refinements in infrared scan—ning, Paley hopes to get back into operation.但是隨著人們重新關(guān)注殺蟲(chóng)劑對(duì)農(nóng)產(chǎn)品的影響，以及紅外線掃描技術(shù)的改進(jìn)，Paley希望能重操舊業(yè)。由此可以推出B項(xiàng)為正確答案。這個(gè)考點(diǎn)與相關(guān)句中的原因狀語(yǔ)(以with引導(dǎo))相聯(lián)系。

　　除了上述原文有因果關(guān)系提示詞的顯性原因考點(diǎn)之外，隱性原因(兩個(gè)句子之間為因果關(guān)系，但無(wú)有關(guān)提示詞)也是常見(jiàn)考點(diǎn)。不管考點(diǎn)是顯性原因，還是隱性原因，原文相關(guān)句出現(xiàn)的格式都是先說(shuō)原因，后說(shuō)結(jié)果，而在題干中通常給出結(jié)果，就其原因提問(wèn)。

　　The application of infrared scanning technology to agriculture met with some diffi-culties due to

　　A. the lack of official support

　　B. its high cost

　　C. the lack of financial support

　　D. its failure to help increase production

　　這道題測(cè)試的考點(diǎn)是一個(gè)隱性原因(原文中沒(méi)有提示詞)。相關(guān)句為第三段前兩句

　　話：第一句話提到將紅外線掃描技術(shù)運(yùn)用于農(nóng)業(yè)遇到困難——Paley的公司于l984年關(guān)閉，第二句話敘述了其中的原因：Farmers：resisted the new technology and long—term backers were hard to find.農(nóng)場(chǎng)主們抵制這項(xiàng)新技術(shù)，而且難以找到(投資方面的)長(zhǎng)期支持者。由此可知C項(xiàng)為正確答案。