It’s 11 ______. We’ll soon have our lunch.

阅读下列说明，回答问题1至问题3。将解答填入答题纸的对应栏内。【说明】小赵是一位优秀的软件设计师，负责过多项系统集成项目的应用开发，现在公司因人手紧张，让他作为项目经理独自管理一个类似的项目，他使用瀑布模型来管理该项目的全生命周期，如下所示：

项目进行到实施阶段，小赵发现在系统定义阶段所制订的项目计划估计不准，实施阶段有许多原先没有估计到的任务现在都冒了出来。项目工期因而一再延期，成本也一直超出。

请简要叙述瀑布模型的优缺点。请简要叙述其他模型如何弥补瀑布模型的不足。

关于稳定型心绞痛的临床特点，正确的是（）

A.心前区刀割样疼痛

B.持续数分钟

C.前胸压榨性疼痛

D.休息或用硝酸酯制剂后消失

E.可放射至心前区和左上肢尺侧

无动性缄默是中枢神经系统哪部分损害引起的意识障碍（）

A.双大脑皮质

B.间脑和脑干

C.脑上部和丘脑网状激活系统

D.中脑腹侧

E.基底节

（2008）图示连接件，两端受拉力P作用，接头的挤压面积为：（）

A.ab

B.cb

C.ιb

D.ιc

Researchers investigating brain size and mental ability say their work offers evidence that education protects the mind from the brain’s physical deterioration.

(46) is known that the brain shrinks as the body ages, but the effects on mental ability are different from person to person. Interestingly, in a study of elderly men and women, those who had more education actually had more brain shrinkage.

"That may seem like bad news," said study author Dr. Edward Coffey, a professor of psychiatry and of neurology at Henry Ford Health System in Detroit.

(47) However, he explained, the finding suggests that education allows people to withstand more brain tissue loss before their mental functioning begins to break down..

The study, published in the July issue of Neurology, is the first to provide biological evidence to support a concept called the "reserve" hypothesis, according to the researchers. In recent years, investigators have developed the idea that people who are more educated have greater cognitive reserves to draw upon as the brain ages; in essence, they have more brain tissue to spare.

(48) Examining brain scans of 320 healthy men and women aged 66 to 90, researchers found that for each year of education the subjects had, there was greater shrinkage of the outer layer of the brain known as the cortex. Yet on tests of cognition and memory, all participants scored in the range indicating normal.

"Everyone has some degree of brain shrinkage," Coffey said. "People lose (on average) 2.5 percent per decade starting in adulthood."

There is, however, a "remarkable range" of shrinkage among people who show no signs of mental decline, Coffey noted. Overall health, he said, accounts for some differences in brain size. Alcohol or drug use, as well as medical conditions such as diabetes and high blood pressure, contribute to brain tissue loss throughout adulthood.

In the absence of such medical conditions, Coffey said, education level helps explain the range of brain shrinkage exhibited among the mentally-fit elderly. The more-educated can withstand greater loss.

(49) Coffey and colleagues gauged shrinkage of the cortex by measuring the cerebrospinal fluid surrounding the brain. The greater the amount of fluid, the greater the cortical shrinkage.

Controlling for the health factors that contribute to brain injury, the researchers found that education was related to the severity of brain shrinkage. For each year of education from first grade on, subjects had an average of 1.77 milliliters more cerebrospinal fluid around the brain. Just how education might affect brain cells is unknown.

(50) In their report, the researchers speculated that in people with more education, certain brain structures deeper than the cortex may stay intact to compensate for cortical shrinkage.

(49) Coffey and colleagues gauged shrinkage of the cortex by measuring the cerebrospinal fluid surrounding the brain. The greater the amount of fluid, the greater the cortical shrinkage.