假设市场是强有效的，那么最好的投资策略是______。 A．通过技术分析投资获得超额

对某班40位同学的一次考试成绩进行统计，频率分布表中，80.5～90.5这一组的频率是0.20，那么成绩在80.5～90.5这个分数段的人数是______．

（12分）

含镁3％－5％的镁铝合金，现已成为轮船制造、化工生产、机械制造等行业的重要原材料。现有一块已知质量的镁铝合金，欲测定其中镁的质量分数，几位同学设计了以下三种不同的实验方案：

回答下列问题：

（1）上述方案中，能测出Mg的质量分数的方案是        （填写代号，下同）

A．实验设计1   B．实验设计2   C．实验设计3  D．都可以

（2）上述方案中的化学反应体现了Mg、Al的性质是           

A．氧化性   B．还原性   C．酸性   D．碱性

（3）某同学设计了右图装置。该装置适合的实验设计是       

用该装置测定镁铝合金中镁的质量分数，所需的实验操作是

             。

A．用排水法测定H₂的体积

B．反应结束后，过滤、洗涤、干燥、称量残渣的质量

C．称量反应前后，装置和药品的总质量

（4）若按实验设计3进行实验。将m g镁铝合金，溶于过量盐酸中，再加入过量的NaOH溶液，可得到白色沉淀，该沉淀物质是         （填化学式）；将此沉淀洗净、干燥后，称得质量为w g。求合金中镁的质量分数                  ；

WASHINGTON－School lunches have been called many things, but a group of retired military officers is giving them a new label: national security threat.

That's not a reference to the mystery meat served up in the cafeteria line either. The retired officers are saying that school lunches have helped make the nation's young people so fat that fewer of them can meet the military's physical fitness standards, and recruitment will be difficult.

A new report being released Tuesday says more than 9 million young adults, or 27 percent of all Americans ages 17 to 24, are too overweight to join the military. Now, the officers are advocating for passage of a wide­ranging nutrition bill that aims to make the nation's school lunches healthier.

The military group acknowledges that other things keep young adults out of the armed services, such as a criminal record or the lack of a high school diploma. But weight problems that have worsened over the past 15 years are now the leading medical reason that recruits are rejected.

Although all branches of the military now meet or exceed recruitment goals, retired Navy Rear Adm. James Barnett Jr., a member of the officers group, says the obesity trend could affect that.

“When over a quarter of young adults are too fat to fight, we need to take notice，” Barnett said. He noted that national security in the year 2030 is “absolutely dependent” on reversing child obesity rates.

This isn't the first time the military has gotten involved in the debate over school lunches. During World War Ⅱ， military leaders had the opposite problem, reporting that many recruits were rejected because of stunted growth and inadequate nutrition. After the war, military leaders pushed Congress to establish the national school lunch program so children would grow up healthier.

Today, the group is urging Congress to eliminate junk food and high­calorie beverages from schools, put more money into the school lunch program and develop new strategies that help children develop healthier habits.

小题1:What is the main problem of the lunches in schools according to the military officers?

A．The meat in the lunches is mysterious.

B．The lunches are too expensive.

C．The lunches contain too much fat.

D．There is inadequate nutrition in the lunches.小题2:The underlined word “obesity” in Paragraph 5 means ________.

A．slow in mind

B．state of being fat

C．quick in movement

D．lack of confidence小题3:Which of the following statements is NOT true?

A．The lunches in American schools are not very healthy.

B．During World War Ⅱ，many people could not join the army because of overweight.

C．According to the author , overweight was the key reason why many recruits were rejected.

D．By now, Congress hasn't eliminated junk food and high­calorie beverages from schools.小题4:Which of the following is the best title for the article?

A．School lunches: a national security threat?

B．National security in danger ?

C．Retired officers tired of school lunches

D．The recruitment of 2030

卫星遥感资料可以及时地提供广大地区的同一时相、同一波段、同一比例尺和什么样的空间信息（）

A.大面积

B.高精度

C.同一精度

D.清晰

男，29岁。3天前因“右上唇痈”入院治疗，今晨起体温急剧上升达39．5℃，相继出现头痛伴恶心，右球结膜淤血，右眼球前突及眼球运动受限，应考虑并发了()

A．脑膜炎

B．脑脓肿

C．败血症

D．脓毒血症

E．海绵窦血栓性静脉炎