问题 选择题

下列现象不可能发生的是:(    )

A.在一与外界绝热的房间内,将一台正在工作的电冰箱的门打开,能使该房间降温。

B.蒸汽机把蒸汽的内能全部转化为机械能

C.一个在粗糙的水平地面上运动的物体最终要停下来,物体的动能全部转化为内能。

D.在热传导中,热量可以自发的从高温物体传向低温物体

答案

AB

在一与外界绝热的房间内,将一台正在工作的电冰箱的门打开,消耗了电能,产生了焦耳热,所以房间温度不光不能降低还会升高,故A不可能发生

蒸汽机把蒸汽的内能不可能全部转化为机械能,转化过程中必然存在能量耗散,故B不可能发生

一个在粗糙的水平地面上运动的物体最终要停下来,物体的动能全部转化为内能,C可能发生

在热传导中,热量可以自发的从高温物体传向低温物体,D可能发生

故选AB

单项选择题
单项选择题

(一)

Motherhood may make women smarter and may help prevent dementia in old age by bathing the brain in protective hormones, US reseachers reported on Thursday.

Tests on rats show that those who raise two or more litters of pups do considerably better in tests of memory and skills than rats who have no babies, and their brains show changes that suggest they may be protected against diseases such as Alzheimer’s. University of Richmond psychology professor Craig Kinsley believes his findings will translate into humans.

"Our research shows that the hormones of pregnancy are protecting the brain, including estrogen, which we know has many neuroprotective effects," Kinsley said.

"It’s rat data but humans are mammals just like these animals are mammals," he added in a telephone interview. "They go through pregnancy and hormonal changes. "

Kinsley said he hoped public health officials and researchers will look to see if having had children protects a woman from Alzheimer’s and other forms of age-related brain decline.

"When people think about pregnancy, they think about what happens to babies and the mother from the neck down," said Kinsley, who presented his findings to the annual meeting of the Society of Neuroscience in Orlando, Florida.

"They do not realize that hormones are washing on the brain. If you look at female animals who have never gone through pregnancy, they act differently toward young. But if she goes through pregnancy, she will sacrifice her life for her infant—that is a great change in her behavior that showed in genetic alterations to the brain. \

What can protect the brain of a woman according to the passage()

A.Estrogen.

B.The hormones of pregnancy.

C.More exercise.

D.Taking care of children.