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如图，在等腰三角形ABC中，AB＝AC，∠A＝50°，直线MN垂直平分边AC，分别交AB，AC于点D，E，则∠BCD＝（　　）

A . 10° B . 15° C . 20° D . 25°

通常人们戴的是一次性医科口罩(SMS)或防雾霾的3M(SMMMS)口罩，二者原料都是聚丙烯。下列说法错误的是（）

A . 丙烯能使酸性高锰酸钾溶液褪色，而聚丙烯不能 B . 丙烯与溴发生加成反应生成 $\text{[math]}$ C . 聚丙烯的结构简式为

D . 聚丙烯属于难降解的物质，随意丢弃会造成白色污染

小梅上街看到诱人的红柿子，买了许多回来吃。柿子是植物的（填组织、器官、细胞等）。首先她把柿子外面一层表皮撕下来，这层表皮属于组织，表皮里面的可食的部分营养丰富，吃时会有许多汁水流出来，这些汁水来自细胞结构的，柿子里还有许多筋络之类的东西，这主要是组织。

在数轴上表示下列各数，并把它们用“ $\text{[math]}$ ”连接起来

$\text{[math]}$ ， $\text{[math]}$ ，0， $\text{[math]}$ ， $\text{[math]}$ ， $\text{[math]}$

高一学生小林利用暑假休息时间，深入自己小区进行实地调查，完成了《关于在社区推动智慧停车的建议》，并提交给当地政府部门。材料说明小林同学是（）

A . 国家机关的监督者 B . 基层自治的决策者 C . 政治生活的参与者 D . 民主管理的实践者

Sometimes, the looks like a boat in the sky.

A . moon B . star C . bird

实验室收集到一桶含有 $\text{[math]}$ 、 $\text{[math]}$ 的废液，他们想从中回收金属铜和硫酸亚铁晶体，设计了如下实验方案。结合实验方案回答下列问题：

（1）步骤 $\text{[math]}$ 中，金属X是。
（2）写出步骤 $\text{[math]}$ 中反应的化学方程式。
（3）步骤 $\text{[math]}$ 和 $\text{[math]}$ 中涉及到的化学反应的基本反应类型为。
（4）在步骤 $\text{[math]}$ 中，还能将金属混合物分离开的物理方法是。

阅读理解

According to a new US study, couples who expect their children to help care for them in old age should hope they have daughters because they are likely to be twice as attentive overall.

The research by Angelina Grigoryeva, a sociologist at Princeton University, found that, while women provide as much care for their elderly parents as they can manage, men do as little as they can get away with and often leave it to female family members.Her analysis of the family networks of 26,000 older Americans concluded that gender(性别) is the most important predictor(预示物) of whether or not people will actively care for elderly parents.

In a paper being presented at the annual conference of the American Sociological Association in San Francisco, she concludes that simply having a sister makes men statistically likely provide less care.

Using data from the University of Michigan Health and Retirement Study, a study which has been tracking a cross-section of over-50s for the last decade, she calculated that women provide an average of 12.3 hours a month of care for elderly parents while men offer only 5.6 hours.

“Whereas the amount of elderly parent care daughters provide is associated with limitations they face, such as employment or childcare, sons' caregiving is associated only with the presence or absence of other helpers, such as sisters or a parent's spouse(配偶),” she explained.

“Sons reduce their relative caregiving efforts when they have a sister, while daughters increase theirs when they have a brother.”

“This suggests that sons pass on parent caregiving responsibilities to their sisters.”

In the UK, the 2011 census(人口普查) showed that there are now around 6.5 million people with caring responsibilities – a figure which has risen by a tenth in a decade.

But many are doing so at the risk of their own health. The census showed that those who provide 50 hours or more of care a week while trying to hold down a full- time job are three times more likely to be struggling with ill health than their working counterparts(相对应的人) who are not carers.

（1） What's the most important factor to predict if people will actively care for the elderly?

A . Gender. B . Education. C . Career. D . Family networks.
（2） The US study finds that .

A . sons are twice likely as daughters to care for parents in old age B . having a sister makes men less likely to do their fair share C . sons and daughters seem to give equal care to their parents D . sons are unwilling to leave caregiving responsibilities to female family members
（3） What does the author stress in the last paragraph?

A . People should give up their jobs to care for the elderly. B . Many care providers work longer hours than others. C . People shouldn't pass on caring responsibilities to others. D . Many care providers have potential health problems.
（4） The author develops the text by .

A . explaining social networks of careers B . describing people's experiences C . analyzing various research and data D . comparing different gender behavior