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两个物体做平抛运动的初速度之比为2∶1，若它们的水平射程相等，则它们抛出点离地面高度之比为[ ]

A．1∶2

B．2∶1

C．1∶4

D．4∶1

答案

答案：C

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下面是《水浒》《西游记》中三个精彩的打虎场面，请写出打虎英雄的名字。

A、在窝里看得仔细，把刀朝母老虎尾底下，尽平生气力，舍命一戳，正中那母老虎粪门。……那老虎朝他一扑，他不慌不忙，趁着那老虎的势力，手起一刀，正中那老虎领下。

B、拽开步，迎着猛虎，道声：“业畜！哪里去！”那只虎礴着身，伏在尘埃，动也不敢动，却被他照头一棒，就打得脑浆迸万点桃红，牙齿喷几珠玉块。

C、左手紧紧地揪住顶花皮，偷出右手来，提起铁锤般大小的拳头，尽平生之力，只顾打。打到五十七拳，那老虎的眼里、口里、鼻子里、耳朵里都迸出了鲜血。

A、                                  B、                                        C、                                        
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[A] Possible ways to keep free from Alzheimer’s
[B] Deficiency of data-collecting in the study
[C] The new findings of ineffectiveness of past cures
[D] Weak evidence of the research
[E] How the new analysis coming from
[F] Future direction of the research concerned
[G] Traditional beliefs in preventive measures

Lifestyle May Not Prevent Alzheimer’s


A comprehensive analysis by an independent government panel has found that there is not enough scientific evidence to date to support the advice doctors currently give—such as exercising, doing crossword puzzles or eating a Mediterranean-style diet—for preventing or controlling symptoms of Alzheimer’s disease and dementia.
(41)______
As rates of age-related dementia and Alzheimer’s disease have continued to rise in the U.S.—largely because Americans are living longer and the over-65 population has swelled to record highs—researchers have worked relentlessly to understand the causes of these mind- robbing diseases and to help prevent or slow their progression. To clarify the state of the current evidence and offer physicians clearer treatment guidelines, the National Institutes of Health (NIH) in early 2009 commissioned a detailed analysis of existing studies, covering 165 papers published between 1984 and 2009.
(42)______
For years, the prevailing hypothesis has been "Use it or lose it" when it comes to avoiding gradual age-related mental decline. Data has associated behaviors such as keeping the mind actively engaged throughout life, staying physically active, eating certain foods and supplementing the diet with specific vitamins and nutrients with lower rates of dementia in old age. These lifestyle factors appeared to limit cognitive decline of various kinds, from occasional "senior moments" to the more serious episodes of cognitive impairment that can be a prelude to Alzheimer’s disease.
(43)______
Now researchers at Duke University report in the current issue of the Annals of Internal Medicine that the data on the preventive effects of lifestyle factors is not as p as they had thought. Led by Brenda Plassman, a professor of psychiatry and behavioral sciences, the study authors analyzed decades’ worth of research, including observational studies in which scientists looked retrospectively at a group of participants to tease out associations between certain behaviors (like exercise) and selected effects (like scores on tests of memory and cognitive skills), as well as the more definitive clinical trials that randomly assign volunteers to intervention or control groups and then assess how the intervention affects cognitive ability.
(44)______
Overall, the researchers say they were dismayed with the paucity and weakness of the existing evidence. "When we applied rigorous but consistent standards to review all the studies, we found that there was not sufficient evidence to recommend any single activity or factor that was protective of cognitive decline later in life, " says Plassman.
(45)______
However weakly, though, the review did support what doctors know about risk factors for cognitive decline: smoking, diabetes, depression, metabolic syndrome and specific gene variants were all linked with increased risk of developing Alzheimer’s disease. In addition, preventive behaviors such as eating a Mediterranean diet, exercising, maintaining cognitive engagement (doing puzzles, learning new things) and fostering extensive social relationships were linked to a lower risk.
The problem is that none of these relationships were particularly robust, the authors say. And none were p enough to justify recommending the behaviors to people who want to prevent or slow down the onset of dementia. The findings led the NIH to issue Monday’s state-of-the-science statement, in which the agency notes, "Currently, firm conclusions cannot be drawn about the association of any modifiable risk factor with cognitive decline or Alzheimer’s disease." Although the statement does not constitute an official policy or government recommendation, it serves as a guideline for doctors advising patients about the best evidence on the role of lifestyle factors in Alzheimer’s prevention.
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