材料一：企业在创造巨大物质财富，促进社会发展的同时，作为对环境造成重大影响的社会组织，理应在保护环境中承担着重要责任。2015年1月1日起，新修订的《环境保护法》正式施行。此次修订，修改和新增了一些重要内容，比如：进一步明确国家支持环境保护科学技术的研发和应用；规定公民应当采用低碳、节俭的生活方式；明确提出对违法排污企业实行按日连续计罚，罚款将上不封顶，从法律层面加大企业环境违法成本和惩罚力度。

材料二：随着我国经济的快速发展，资源浪费、环境污染和生态破坏等问题日益突出，1989年起实施的《环境保护法》存在的缺陷日益凸现，如政府对环境质量负责的约束机制和责任追究制度缺乏、环境执法强制力不够等等。2011年该法修订正式启动，公开征求意见14182条，2014年4月24日，十二届全国人大常委会第八次会议表决通过了修订后的《环境保护法》，为各地政府履行相关职能提供了有力的法律保障。

细胞分裂过程中，细胞内变化最明显的是（   ）

前不久，一张猫咪走在楼梯上的图片(见右图)掀起了一轮争论热潮。对于这只猫究竟是在上楼还是在下楼，网友有不同的看法和理由。这说明(　　)

阅读短文，下列问题。

      Helen Keller lived in the US. She was a great woman. When Helen was a baby, she often got ill. After a few years, she heard nothing, she saw nothing, and she couldn’t speak to other people.

     When one day, a teacher came to live with Helen and her family. The teacher helped Helen learn about words. Helen was a bright child and soon she learned to spell her first word. When she was older, she went to college（大学）.

     Helen was very famous. She helped many blind and deaf people. She went around the world and helped many people.

Helen was a very old woman when she died. Today, the world remembers her. She was blind and deaf, but she found a way to see and to hear.

下面关于加速度的描述中，正确的是（   ）