对冠脉血流量进行调节的各种因素中，最重要的是（） A.心肌本身的代谢水平 B.交感神

    最近欧洲天文学家宣布在太阳系外发现了一颗类地行星，该行星可能适合生命居住。与地球相比，该行星

    ①质量与地球相似 ②公转方向与地球一致 ③有卫星环绕 ④离恒星的距离适中 [ ]

A、①②

B、②③

C、③④

D、①④

女性，38岁。出现恶心呕吐，呕吐物较多带粪臭味。该患者可能是（）

A.胃潴留

B.肠梗阻

C.尿毒症

D.中毒

E.幽门梗阻

甲型H1N1流感病例的密切接触者的医学观察期限为（）天。

A、3

B、5

C、7

D、9

阅读理解。

     Motherhood may make women smarter and may help prevent dementia (痴呆) in old age by bathing the

brain in protective hormones (荷尔蒙), U.S. researchers 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 (早老痴呆症). University of Richmond psychology professor

Craig Kinsley believes his findings will translate into humans.

     "Our research shows that the hormones of pregnancy (怀孕) are protecting the brain, including estrogen

(雌激素), which we know has many neuroprotective (保护神经的) 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 that have never

gone through pregnancy, they act differently toward the 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 (改变)

to the brain."

1. How do scientists know "Motherhood may make women smarter"?

A. Some researchers have told them.

B. Many women say so.

C. They know it by experimenting on rats.

D. They know it through their own experience.

2. What does the phrase "litters of pups" mean in the second paragraph?

A. Baby rats.

B. Animals.

C. Old rats.

D. Grown-up rats.

3. 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.

4. "It's rat data but humans are mammals just like these animals are mammals." What does

the sentence suggest?

A. The experiments on the rats have nothing to do with humans.

B. The experiments on the rats are very important for animals.

C. The experiments on the rats are much the same on humans.

D. The experiments on the rats are much the same on other animals.

凝汽器形成真空的原理？