列竖式计算。（1）3.78×2.9（2）15÷74（保留两位小数）（3）72.9

从太空看地球，它是一个美丽的蔚蓝色的星球，这是因为（　　）

A．地球表面有大面积的森林

B．地球上污染严重

C．地球上七分是海洋，三分是陆地

D．地球被云层包围

实验室用含有少量碳酸镁杂质的块状碳酸钙与盐酸反应制取二氧化碳．

（1）通过长颈漏斗向放有块状碳酸钙的大试管中加入足量的盐酸，充分反应，在大试管中可以观察到的现象是______

（2）反应完毕，欲从反应液中制取少量纯净的氯化钙晶体，拟进行下列几项操作：

①蒸发  ②过滤  ③加入适量的X溶液

X的化学式是______；上述几项操作正确的顺序是______（填序号）

（3）进行蒸发时除了用到铁架台、铁圈和下述提供的仪器外还缺的仪器是______、

______，其中______（填仪器名称）是进行过滤和蒸发时都要使用，但使用目的各不相同的玻璃仪器．

（4）过滤时，某同学向漏斗倾倒液体，不小心使漏斗的液面超过了滤纸的边缘，这时，该同学应进行的操作是______．

空气中含量居第二位的元素跟地壳中含量居第二位的元素形成的化合物的化学式是（　　）

A．NO₂

B．SiO₂

C．Al₂O₃

D．Fe₃O₄

It is found that American students spend less than 15% of their time in school. While there’s no doubt that school is important, a number of recent studies reminds us that parents are even more so. A study published earlier this month by researchers at North Carolina State University, for example, finds that parental involvement — checking homework, attending school meetings and events, discussing school activities at home — has a more powerful influence on students’ academic performance than anything about the school the students attend. Another study, published in the Review of Economics and Statistics, reports that the effort put forth by parents (reading stories aloud, meeting with teachers) has a bigger impact on their children’s educational achievement than the effort devoted by either teachers or the students themselves. And a third study concludes that schools would have to increase their spending by more than $1,000 per pupil in order to achieve the same results that are gained with parental involvement.

So parents matter. But it is also revealed in researches that parents, of all backgrounds, don’t need to buy expensive educational toys or digital devices for their kids in order to give them an advantage. They don’t need to drive their offspring (子孙，后代)to enrichment classes or test-preparation courses. What they need to do with their children is much simpler: talk.

But not just any talk. Recent research has indicated exactly what kinds of talk at home encourage children’s success at school. For example, a study conducted by researchers at the UCLA School of Public Health and published in the journal Pediatrics found that two-way adult-child conversations were six times as potent in promoting language development as the ones in which the adult did all the talking. Engaging in this reciprocal（双向的) back-and-forth gives children a chance to try out language for themselves, and also gives them the sense that their thoughts and opinions matter.

The content of parents’ conversations with kids matters, too. Children who hear talk about counting and numbers at home start school with much more extensive mathematical knowledge, report researchers from the University of Chicago. While the conversations parents have with their children change as kids grow older, the effect of these exchanges on academic achievement remains strong. Research finds that parents play an important role in what is called “academic socialization” — setting expectations and making connections between current behavior and future goals. Engaging in these sorts of conversations has a greater impact on educational accomplishment.

小题1:Parents are even more important than schools because ______.

A．parental involvement makes up for what schools are not able to do

B．teachers and students themselves do not put in enough effort

C．parental involvement saves money for schools and the local government

D．students may well make greater achievements with parents' attention小题2:It can be inferred from the 2^nd paragraph that ______.

A．educational toys are unaffordable nowadays

B．digital devices can give children an advantage

C．some parents believe in enrichment classes

D．talking with children is a very simple task小题3:The word "potent" is closest in meaning to ______.

A．powerful

B．difficult

C．necessary

D．resistant小题4:Which of the following will more encourage children's success at school according to the passage?

A．Parents order their children to stop playing video games.

B．Parents discuss with their children the possible future career.

C．Parents lecture their children on getting too low marks on tests.

D．Parents introduce colleges around the US to their children.

社会竞争，是指在人类生活中，个人或团体为了取得或利用某种有限事物，以达到占有为目的，不顾他方的努力，而发生的彼此相互争夺的一种行为。下列不属于社会竞争的一项是( )。

A．人类在进化过程中，为争取基本生存权而进行的战争

B．商品社会里，商人为了占得市场，花大量的钱做广告

C．无产阶级领导的革命和斗争，主要是为了用社会主义制度取代资本主义制度

D．王阳明一个人在后院看竹子格物致知