已知抛物线y=ax2+2ax+4(0x2, 且x1+x2=1－a, 则 （） A

孕激素分泌的高峰期出现在（）

A.子宫内膜增生期

B.黄体期

C.排卵期

D.卵泡期与黄体期

E.月经期

维生素C主要存在于蔬菜、水果中，它能促进人体生长发育，增强对疾病的抵抗力，近年研究发现它还有防癌作用．某同学为了探究维生素C的元素组成，将少量维生素C放在氧气中完全燃烧后，得到了二氧化碳和水，则该同学能得到的正确结论是（　　）

A．维生素C中一定含有C、H、0元素

B．维生素C中一定含有C、H元素、可能含有0元素

C．维生素C中一定含有C、0元素，可能含有H元素

D．维生素C中一定含有C元素，可能含有H、0元素

神经纤维（）

A．Cajal染色法

B．Weigert-Pal染色法

C．Lillie-Masson二胺银染色法

D．Holmes染色法

E．焦油紫染色法

The new SAT scores are out, and buried in them is a sign of hope for American education. True, the scores are actually a bit lower than last year’s; the combined average for the SAT’s math and reading sections fell 7 points, to 1021, the biggest decrease since 1975, when the score dropped 16 points, to 1010. But statistically speaking, a 7-point decline (out of a possible 1600 on those two sections) isn’t much. It’s less than the value of a single question, which is about 10 points. Also, the SAT was radically changed last year. The College Board made it longer and added Algebra [1 , more grammar and an essay. Fewer kids wanted to take the new 3—hr and 45—min. test more than once, so fewer had an opportunity to improve their performance. Scores were bound to slide.
But tucked into the reams of data the College Board included with the new scores was some wonderful news. I was wrong. In 2003 I spent six months tracking the development of the new SAT. I sat through hours of test-development sessions and even learned how to grade SAT essays. TIME ran my resulting story on its cover that October.
The story did make some predictions that turned out to be right. For instance, the new test favors girls more than the old one did. It is a long-standing tenet of testmaking that girls outperform boys on writing exams. For reasons I am not foolish enough to speculate about in print, girls are better than boys at fixing grammar and constructing essays, so the addition of a third SAT section, on writing, was almost certain to shrink the male-female score gap. It did. Girls trounced boys on the new writing section, 502 to 491. Boys still outscored girls overall, thanks largely to boys’ 536 average on the math section, compared with girls’ 502. But boys now lead on the reading section by just 3 points, 505 to 502; the gap was 8 points last year. What changed The new test has no analogies ("bird is to nest" as "dog is to doghouse"), and boys usually clobbered girls on analogies.
My story also predicted that the addition of the writing section would damage the SAT’s reliability. Reliability is a measure of how similar a test’s results are from one sitting to the next. The pre-2005 SAT had a standard error of measurement of about 30 points per section. In other words, if you got a 500 on the math section, your "true" score was anywhere between 470 and 530. But the new writing section, which includes not only a multiple-choice grammar segment but also the subjective essay, has a standard error of measurement of 40 points. That means a kid who gets a 760 in writing may actually be a perfect 800-or a clever-but-no-genius 720. In short, the College Board sacrificed some reliability in order to include writing.
Finally, I was right about one other thing, that the graders would reward formulaic, colorless writing over sharp young voices. The average essay score for kids who wrote in the first person was 6.9, compared with 7. 2 for those who didn’t. (A 1-to-12 scale is used to grade essays. That score is then combined with the score on the grammar questions and translated into the familiar 200 to 800 points. ) As my editors know well, first-person writing can flop. But the College Board is now distributing a guide called "20 Outstanding SAT Essays"-all of them perfect scores-and many are unbearably mechanical and cliched.
Still, there’s good news. The central contention of my 2003 story was that the SAT’s shift from an abstract-reasoning test to a test of classroom material like Algebra II would hurt kids from failing schools. I was worried that the most vulnerable students would struggle on the new version. Instead, the very poorest children-those from families earning less than $20,000 a year—improved their SAT performance this year. It was a modest improvement (just 3 points) but significant, given the overall slump in scores. And noncitizen residents and refugees saw their scores rise an impressive 13 points. It was middleclass and rich kids who account for the much reported decline.
What explains those wonderfully unpredictable findings The College Board has no firm answers, but its top researcher, Wayne Camara, suggests a (somewhat self-serving) theory: the new SAT is less coachable. When designing the new test, the board banned analogies and "quantitative comparisons". "I think those items disadvantaged students who did not have the resources, the motivation, the awareness to figure out how to approach them," says Camara. "By eliminating those, the test becomes much less about strategy. " Because it focuses more on what high schools teach and less on tricky reasoning questions, the SAT is now more, not less, egalitarian. Sometimes it’s nice to be wrong.

What does Wayne Camara mean by saying that "the new SAT is less coachable" (para. 7)

将6.854500修约为三位有效数字

A．3.2
B．6.85
C．3.3
D．2.82
E．2.81