下列说法正确的是( ) A.每一周期元素都是从碱金属开始,以稀有气体结束 B.f

题型:选择题

问题:

下列说法正确的是(  )

A.每一周期元素都是从碱金属开始,以稀有气体结束

B.f区都是副族元素,s区和p区的都是主族元素

C.已知在20℃1molNa失去1mol电子需吸收650kJ能量,则其第一电离能为650KJ/mol

D.Ge的电负性为1.8,则其是典型的非金属

考点:元素周期表
题型:选择题

Some kinds of mental skills naturally decrease as people get older. Yet research seems to show that some training can improve such skills. A recently published study also appears to demonstrate that the good effects of training can last for many years after that training has ended.

Researchers at Johns Hopkins University in Maryland wanted to learn how long memory and thinking skills would last in older people who trained to keep them. The people were part of the ten-year research project. They were taught methods meant to improve their memory, thinking and ability to perform everyday tasks.

More than 2,800 volunteered for the study called ACTIVE - short for Advanced (Cognitive) Training for Independent and Vital Elderly. Most studied when they were more than 70 years old.

The volunteers took one of several short training classes meant to help them keep their mental abilities. One class trained participants in skills including how to remember word lists. Another group trained in reasoning. A third group received help with speed-of-processing - speed of receiving and understanding information. A fourth group - the control group did not get any training.

Earlier results had established that the training helped the participants for up to five years. Now, lead study writer George Rebok says, the research showed most of the training remained effective a full ten years later.

Professor Rebok and his team found that the people trained in reasoning and speed-of-processing did better on tests than the control group.

"We are wondering whether those effects which endured over time would still be there ten years following the training, and in fact, that's exactly what we found."

The effect on memory, however, seemed not to last as long. Still, the old people in any of the three classes generally reported less difficulty in performing daily activities than the control group. The total training time for the older people was between 10 and 15 hours.

小题1:Which statement is true according to the text?

A.This kind of training can only have effect on people for a few years。

B.The people were trained during a period of ten years.

C.All the people who were studied were more than 70 years old.

D.The second group were trained how to remember word lists.小题2:What can be inferred from the passage?

A.There were four groups being trained.

B.The old people trained can remember words better.

C.The second and third group improved their skills better than the first one.

D.The research showed that the effect of the training could absolutely last 10 years.小题3:What’s the main idea of the fourth paragragh?

A.What was the meaning of the research?

B.How was the research conducted?

C.Why was the mental training effective?

D.How long did the research last?小题4:What is the best title of the passage?

A.Mental Training Helped Elderly Stay Sharp for Years

B.How to improve our mental health

C.Four groups of old people were trained mentally.

D. The result of a ten-year research

题型:选择题
方程
3
x
=
4
70-x
的解是______.
题型:选择题

所谓合理用药是指()

A.对症开药

B.以客观实际或科学知识为基础的高层次的用药

C.价格低廉

D.安全用药

E.以药物和疾病系统知识为基础,安全、有效、经济、适当地用药

题型:选择题

电流互感器二次侧接地是为了()。

A.测量用;

B.工作接地;

C.保护接地;

D.节省导线。

题型:选择题

根据FCOM能确定一个未曾颁发起飞图表的机场起飞性能吗()

A.能,但都很保守

B.能,只要计算正确,都非常精确

C.不能

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