托福阅读长难句21天训练营Day(19).docx

长难句解析21天训练营Dayl91. Continued sedimentationthe process of deposits' settling on thesea bottomburies the organic matter and subjects it to highertemperatures and pressures, which convert the organic matter to oil andgas.2. As muddy sediments are pressed together; the gas and small dropletsof oil may be squeezed out of the mud and may move into sandy layersnearby.3. Both oil and gas are less dense than water, so they generally tend torise upward through water-saturated rock and sediment4. When the well reaches a pool, oil usually rises up the well because ofits density difference with water beneath it or because of the pressure ofexpanding gas trapped above it.5. Water or steam may be pumped down adjacent wells to help push theoil out.6. The development of the oil field on the North Slope of Alaska and theconstruction of the Alaska pipeline are examples of the great expenseand difficulty involved in new oil discoveries.7. Offshore drilling platforms extend the search for oil to the ocean, scontinental shelvesthose gently sloping submarine regions at theedges of the continents.8. It may be in a pool too small or too far from a potential market tojustify the expense of drilling.9. Offshore platforms may also lose oil, creating oil slicks that drift ashoreand foul the beaches, harming the environment.10. The Wilmington field near Long Beach, California, has subsided ninemeters in 50 years; protective barriers have had to be built to preventseawater from flooding the area.11. While there are a dozen or more mass extinctions in the geologicalrecord, the Cretaceous mass extinction has always intriguedpaleontologists because it marks the end of the age of the dinosaurs.