To prevent the deserts coming near, China has planted billions of trees---to replace destroyed forests and as barriers against the sand. This isn’t a cure, though, say experts, as thirsty trees can make the problem worse by taking in groundwater.

“Planting tress is one way, but it isn’t that simple. It doesn’t solve the basic issue of water resources,” says Wu Bo, a professor. “We need to calculate how much water the trees will absorb, or else it could have a negative effect.”

Villagers in Zhengxin have taken on this challenge, with limited success. When the irrigation channels began to run dry, Lu Xianglin switched from wheat to cotton on his land. He also planted trees to protect his fields from sandstorms. He says he still gets good yields using flood irrigation and earns a good income for his family.

Other farmers haven’t stuck it out: About one in three have left Zhengxin in the past 10 years after their wheat crops died. Young people who can find jobs in the towns rarely return.

Last week, Mr Lu joined the other men in his village on a government-arranged trip to see the land that has been set aside for their relocation, nearly 40 miles to the south. The next day, he was back, shaking his head at the plan. The idea of uprooting his family troubles him, as does the idea of giving up the land that fed his forefathers. He prefers to stay and keep up the fight.

“With enough water, this problem can be solved,” Lu says. “We can plant trees and grass, and they will grow bigger. That will stop the desert.”

Experts say that farmers could switch to drip irrigation to lessen their water intake for growing crops. Elsewhere in the region, farmers have built brick greenhouses as part of a plan to grow vegetables using less water. Roadside signs urge farmers to “Save Water, Protect the Environment”.

 

49. The negative effect of planting trees in deserts is that __________.

   A. it can make groundwater become less

   B. it can prevent the sand moving freely

   C. it can stop crops growing well

   D. it can get the soil to become poor

50. Why did Mr Lu NOT accept the idea of relocation?

   A. Because the plan of relocation will cost him much money.

   B. Because his family had trouble moving away.

   C. Because he was reluctant to give up his land.

   D. Because he would rather stay than fight against the deserts.

51. What can we infer from the passage?

   A. The deserts drive more and more people to leave their homes for their lives.

   B People have no means to fight against the land becoming desert

   C. Water is the biggest barrier for people to stop the desert.

   D. Planting trees cannot solve the problem of desertification of farmland

52. What advice is given by experts to save water?

   A. To plant more trees         B. To build greenhouses

   C. To change crops             D. To use drip irrigation. 

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 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．”
【小题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．

【小题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．

【小题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．

【小题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．

【小题5】Which title is the best for this passage?

A．Do You Want to Be Smarter?

B．Motherhood Makes Women Smarter

C．Mysterious Hormones

D．An Important Study

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 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(改变) to the brain.”
【小题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.

【小题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.

【小题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.

【小题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.

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 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 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 （改变） to the brain.”
【小题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.

【小题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.

【小题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.

【小题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.

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 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(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.