ZX7系列电焊机是（）焊机。A.多特性 B.点焊 C.逆变式 D.对焊

America is growing older. Fifty years ago, only 4 out of every 100 people in the United States were 65 or older. Today,10 out of every 100 Americans are over 65. The aging of the population will affect American society (社会) in many ways —education, medicine, and business. Quietly, the growing of America has made us a very different society —one in which people have a quite different idea of what kind of behavior is suitable at various ages.

A person’s age no longer tells you anything about his/her social position (职位、地位), marriage or health. There’s no longer a particular year in which one goes to school or goes to work or gets married or starts a family. The social clock that kept us on time and told us when to go to school, get a job, or stop working isn’t as strong as it used to be. It doesn’t surprise us to hear of a 29-year-old university president or a 70-year-old man who has become a father for the first time. Public ideas are changing.

Many people say, ‘I am much younger than my mother—or my father—was at my age.’ No one says ‘ Act your age’ any more. We’ve stopped looking with surprise at older people who act in youthful ways.

小题1:It can be learnt from the text that the aging of the population in America ______.

A．has made people feel younger

B．has changed people’s social position

C．has changed people’s understanding of age

D．has slowed down the country’s social development小题2:The underlined word ‘one’ in the first paragraph refers to____.

A．a society

B．America

C．a place

D．population小题3:."Act your age " in the last paragraph means people should ______.

A．be active when they are old

B．do the right thing at the right age

C．show respect for their parents young or the old

D．take more physical exercise suitable to their age小题4:If a 20-year-old man becomes general manager of a big company, the writer of the text would most probably consider it ______.

A．normal

B．wonderful

C．unbelievable

D．unreasonable

某化学课外活动兴趣小组在研究“铁丝在氧气中燃烧的影响因素”实验时，需要制取一定量的氧气．如图是该小组甲、乙、丙、丁四位同学设计的几种制氧气的装置及选用的试剂．回答下列问题：

（1）写出甲同学制取氧气的化学反应方程式：______．

（2）从装置和选用的试剂分析，有错误的是______（填“甲”、“乙”、“丙”、“丁”）．

（3）写出丁同学所用装置中一种玻璃仪器的名称：______（导管和橡皮塞除外）．

（4）甲同学制取并收集一瓶氧气后，做铁丝在氧气中燃烧的实验，结果未看到火星四射的现象，你认为影响甲同学实验失败的可能因素是______（写出一个即可）．

（5）丙同学实验时取用了15%的过氧化氢溶液20mL（设密度为1g/mL），则所取溶液中含H₂O₂______g，实验后要回收MnO₂，应采取的实验基本操作是______．

下列瓣膜病，出现水冲脉的是（）

A.肺动脉瓣狭窄

B.二尖瓣狭窄

C.二尖瓣关闭不全

D.主动脉瓣狭窄

E.主动脉瓣关闭不全

个人独资企业投资人可以自行管理企业事务，也可以委托其他人负责企业的事务管理。 ( )

女性，62岁，患慢性支气管炎16年，今日又患声带水肿，请你为患者做面罩吸氧。