金属钛（Ti）是重要的航空航天材料。金属钛可以由TiO2与Si高温制取，反应的化

有一片青草地，每天都匀速地长出青草，这篇青草可供他7头牛吃6周或供他多头牛吃4周，那么这片草地可供他w头牛吃几周？

Many people have come to realise that they should go on________balanced diet and

make_________ room in their day for exercise.                           [ ]

A. a; /      

B. the; a    

C. the; the   

D. /; a

材料一：胡 * * * * 在中央人口资源环境工作座谈会上强调，全面落实科学发展观，进一步调整经济结构和转变经济增长方式，使经济增长建立在提高人口素质、高效利用资源、减少环境污染、注重质量效益的基础上，努力建设资源节约型、环境友好型社会。

材料二：广州创建全国环保模范城市，取得了一定的成绩。据有关报道：广州公交出租车年内将告别“冒黑烟”！2006年底，广州逾2.4万辆公交出租车将基本完成LPG（液化石油气）清洁燃料改造。年少排一氧化碳逾2万吨。省社科院环境经济与政策研究中心在《清洁替代燃料汽车发展实证研究》报告提出，如果珠三角区域化整体推广LPG替代燃料汽车，LPG的潜在市场估计达到200万吨，可实现替代汽柴油180万吨。这将极大缓解广东成品油的供给压力，减轻珠三角地区公路交通对燃油的依赖。

（1）为实现人与自然和谐共处，建设资源节约、环境友好型社会，我国必须坚持哪些基本国策和战略？

                                                                                                                                                               （2）请你针对浪费能源的不良现象，为节约能源设计一则公益广告。

（3）请你结合广州创建全国环保模范城市活动，谈一谈中学生应该怎样做。 

自吸式离心泵的结构形式按涡壳形式分为单涡壳式和双涡壳式两种。（）

(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. \

"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.