【正文】 Bold Face Practice 1. Modern navigation systems, which are found in most of today’s mercial aircraft, are made with lowpower circuitry, which is more susceptible to interference than the vacuumtube circuitry found in older planes. (Fact) During landing, navigation systems receive radio signals from the airport to guide the plane to the runway. (Principle) Recently, one plane with lowpower circuitry veered off course during landing, its dials dimming, when a passenger turned on a laptop puter. (Evidence) Clearly, modern aircraft navigation systems are being put at risk by the electronic devices that passengers carry on board, such as cassette players and laptop puters. (Conclusion) 2. A doubleblind study, in which neither the patient nor the primary researcher knows whether the patient is being given the drug being tested or a placebo, is the most effective procedure for testing the efficacy of a drug. (Principle) But we will not be able to perform such a study on this new drug, since the drug will have various effects on the patients’ bodies, which will make us aware of whether the patients are getting the drug or a placebo. (AntiConsideration) 3. The interstitial nucleus, a subregion of the brain’s hypothalamus, is typically smaller for male cats than for female cats. (Fact) A neurobiologist performed autopsies on male cats who died from disease X, a disease affecting no more than percent of male cats, and found that these male cats had interstitial nuclei that were as large as those generally found in female cats. (Evidence) Thus, the size of the interstitial nucleus determines whether or not male cats can contract disease X,(Consideration that can be drawn from the first one) but, the hypothalamus is known not to be causally linked to disease Y, and disease X is a subtype of disease Y. (Fact) 4. More and more puter programs that provide solutions to mathematical problems in engineering are being produced, and it is thus increasingly unnecessary for practicing engineers to have a thorough understanding of fundamental mathematical principles. (Conclusion) Consequently, in training engineers who will work in industry, less emphasis should be placed on mathematical principles, so that space in the engineering curriculum will be available for other important subjects. (Conclusion) 5. Gasolinepowered boat engines manufactured in the a North American country prior to 1990 contribute significantly to the pollution found in the world’s oceans. (Fact) In 1990, however, the government imposed stricter pollution controls on gasoline engines manufactured for boats, and beginning in 1995, the government imposed a program of inspections for pre1990 boat engines with increasingly rigorous pollution standards. (Fact) As the older boat engines fail to pass inspection, boat owners are increasingly retiring their old engines in favor of newer, lesspolluting boat engines. (The evidence showed in the patten of cause and effect ) As a result, the amount of pollution these older boat engines emit into the world’s oceans will steadily decrease over the next ten years. (Conclusion) 6. Plants that exhibit certain leaf diseases tend to measure extremely high in the amount of zinc in their leaf and stem tissue. (Fact or Background) Botanists have discovered that phosphorus of the type typically used in a phosphorushigh fertilizer reacts with the zinc in such a way as to prevent treated plants from exhibiting the leaf diseases, and zinc is the cause and not merely an effect of the leaf diseases. (The second evidence found by the author of passage) Thus, plants can be cured from these leaf diseases by the use of a fertilizer high in phosphorus. (Conclusion) 7. To be accepted as a member at the Brown Country Club, one must have a worth of over ten million dollars and must not have any connections t