老托福阅读真题PASSAGE 90【荐】.pdfVIP

老托福阅读真题PASSAGE 90 托福阅读的思维方式就是托福阅读的出题方式，只有掌握了这种思维方式，才有可能在做题之 前，预测到新托福阅读题的出题形式和特点，为找答案节省时间。老托福阅读试题的核心价值，在 于其最贴近真题的阅读思维方式。此外老托福阅读真题比新托福IBT阅读文章要短，比较容易适应。 这也是大家在备考托福的时候非常重要 的一点。因为前期的入手如果能从容易的开始，就会形成一 个循序渐进的过程方式，让大家的练习有一个提高的过程。 既然老托福阅读试题有这样的效果，那我们如何利用那有限的真题来达到锻炼自己的目的呢? 事实上这就一个办法，就是坚持。本期为大家推荐老托福阅读的真题PASSAGE 90，有原文及答案， 希望对托福考生备考有所帮助。 Perhaps one of themost dramatic and importantchanges that took place intheMesozoic eraoccurred lateinthatera,amongthesmallorganismsthatpopulatetheuppermost, sunlit portion of the oceans — the plankton. The term plankton is a broad one, designating all of the small plants and animals that float about or weakly propel themselves through the sea.Inthe latestagesof theMesozoic era,duringtheCretaceousperiod, therewas a great expansionofplanktonthatprecipitated skeletonsorshellscomposedoftwotypesofmineral: silica and calcium carbonate. This development radically changed the types of sediments that accumulated on the seafloor,because,while theorganicpartsoftheplanktondecayedaftertheorganismsdied, their mineralized skeletons often survived and sank to the bottom. For the first time in theEarths longhistory,very largequantitiesof silicaskeletons,whichwould eventually harden into rock, began to pile up in parts of the deep sea. Thick deposits of calcareous ooze made up of the tiny remains of the calcium carbonate-secreting plankton also accumulated as never before. The famous white chalk cliffs of Dover, in the southeast of England, are just one example of the huge quantities of such material that amassed during theCretaceousperiod;therearemanymore.Justwhythecalcareousplanktonwere soprolific duringthelatterpartoftheCretaceousperiod isnotfullyunderstood.Suchmassiveamounts of chalky sediments have never since been deposited over a comparable period of time. The high biological productivity of theCretaceous oceans also ledto idealc