3. What constitutes a major threat to the survival of turtles according to Elizabeth Griffin?

　　A.Their inadequate food supply.

　　B.Unregulated commercial fishing.

　　C.Their lower reproductively ability.

　　D.Contamination of sea water

　　4. How does global warming affect the survival of turtles?

　　A.It threatens the sandy beaches on which they lay eggs.

　　B.The changing climate makes it difficult for their eggs to hatch.

　　C.The rising sea levels make it harder for their hatchlings to grow.

　　D.It takes them longer to adapt to the high beach temperature.

　　5. The last sentence of the passage is meant to ________.

　　A.persuade human beings to show more affection for turtles

　　B.stress that even the most ugly species should be protected

　　C.call for effective measures to ensure sea turtles’ survival

　　D.warn our descendants about the extinction of species

　　Passage Two

　　There are few more sobering online activities than entering data into college-tuition calculators and gasping as the Web spits back a six-figure sum. But economists say families about to go into debt to fund four years of partying, as well as studying, can console themselves with the knowledge that college is an investment that, unlike many bank stocks, should yield huge dividends.

　　A 2008 study by two Harvard economists notes that the “labor-market premium to skill”—or the amount college graduates earned that’s greater than what high-school graduate earned—decreased for much of the 20th century, but has come back with a vengeance (報復性地) since the 1980s. In 2005, The typical full-time year-round U.S. worker with a four-year college degree earned $50,900, 62% more than the $31,500 earned by a worker with only a high-school diploma.

　　There’s no question that going to college is a smart economic choice. But a look at the strange variations in tuition reveals that the choice about which college to attend doesn’t come down merely to dollars and cents. Does going to Columbia University (tuition, room and board $49,260 in 2007-08) yield a 40% greater return than attending the University of Colorado at Boulder as an out-of-state student ($35,542)? Probably not. Does being an out-of-state student at the University of Colorado at Boulder yield twice the amount of income as being an in-state student ($17,380) there? Not likely.