15. The author mentions all of the following as effects of mass transportation on cities EXCEPT

　　（A） growth in city area

　　（B） separation of commercial and residential districts.

　　（C） Changes in life in the inner city.

　　（D） Increasing standards of living.

　　16. The word "vast" in line 5 is closest in meaning to

　　（A） large

　　（B） basic

　　（C） new

　　（D） urban

　　17. The word "sparked" in line 15 is closest in meaning to

　　（A） brought about

　　（B） surrounded

　　（C） sent out

　　（D） followed

　　18. Why does the author mention both Boston and Chicago？

　　（A） To demonstrate positive and negative effects of growth.

　　（B） To show that mass transit changed many cities.

　　（C） To exemplify cities with and without mass transportation.

　　（D） To contrast their rates of growth

　　19. The word "potential" in line 23 is closest in meaning to

　　（A） certain

　　（B） popular

　　（C） improved

　　（D） possible

　　20. The word "many" in line 25 refers to

　　（A） people

　　（B） lots

　　（C） years

　　（D） developers

　　21. According to the passage， what was one disadvantage of residential expansion？

　　（A） It was expensive.

　　（B） It happened too slowly.

　　（C） It was unplanned.

　　（D） It created a demand for public transportation.

　　22. The author mentions Chicago in the second paragraph as an example of a city

　　（A） that is large

　　（B） that is used as a model for land development

　　（C） where land development exceeded population growth

　　（D） with an excellent mass transportation system.

　　Question 23-33

　　The preservation of embryos and juveniles is rare occurrence in the fossil record. The tiny， delicate skeletons are usually scattered by scavengers or destroyed by weathering before they can be fossilized. Ichthyosaurs had a higher chance of being preserved than did terrestrial creatures because， as marine animals， they tended to live in environments less subject to erosion. Still， their fossilization required a suite of factors： a slow rate of decay of soft tissues， little scavenging by other animals， a lack if swift currents and waves to jumble and carry away small bones， and fairly rapid burial. Given these factors，some areas have become a treasury of well-preserved ichthyosaur fossils.