课外小科约老师继续探究铁粉和硫粉反应的实验：他们各自取一定量的铁粉和硫粉均匀混合后放在石棉网上，在其中插入烧红的玻璃棒，反应立即发生，拿掉玻璃棒后，反应继续剧烈进行，反应过程中有少量刺激性气味的气体X产生，反应结束后，都得到黑色固体，老师得到的黑色固体不会被磁铁吸引，而小科的却会被磁铁吸引。

（1）铁和硫的反应是　 　（填“放热”或“吸热”）反应。

（2）气体X的化学式为　         　。

（3）对比老师的实验结果，小科猜想自己得到的黑色固体可能是有剩余的铁或有生成的四氧化三铁，小科想验证是否有铁剩余，老师启发小科：硫化亚铁能与稀硫酸反应，产生硫化氢气体，该气体能被氢氧化钠溶液吸收。于是，小科认为正确连接如图所示的三个装置并进行实验，如果a处有水压出，就能验证有铁剩余．

①小科依次连接各装置的导管口：e→　     　→b→a（填“c→d”或“d→c”）

②老师指出设计不够合理，不能就此验证猜想。请你帮小科说出不够合理的原因：　       　。于是小科改进了实验设计，继续进行实验…

Q:____ ?

A: No, I' m not. I' m____than her. l am afraid of speaking in front of people.

下列实验方案或操作，你认为可行的是（　　）

​

C

    The government in China plans to end its one-child policy (政策) and let families have two children instead. The plan was meant to balance (平衡) population development and stop a falling birth rate (出生率).

    China started the one-child policy in the 1980s. But the government allowed only a small number of couples to have two children. For example, some families in the countryside could have two children, if the first-born child is a girl. In 2013, the Chinese government gave other couples a chance to have two children if one of them was an only child.

    Jiang Quanbao, a population expert, explained how Chinese families react to the newest policy. "Lots of young people in the cities are no longer interested in having a second child," he said.

    At the end of 2014, China had a population of 1.37 billion people. But the labor market population will drop in 35 years. That is to say, the country will be in great need of labor by the year 2050. With the "two children" policy, an increase in births can solve this problem.