题干

英国医生赛达尼•任格在对离体蛙心进行灌注实验时发现:用不含钙和钾的生理盐水灌注,蛙心收缩不能维持;用少量钙和钾的生理盐水灌注,蛙心可持续跳动数小时.该实验说明钙盐和钾盐(    )

A:是心肌组织细胞的重要组成成分

B:为蛙心的持续跳动提供足够的能量

C:对维持生物体的生命活动有重要作用

D:对维持心肌细胞的形态有着重要作用

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答案(点此获取答案解析)

C

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阅读理解

    Have you ever run into a careless cell phone user on the street? Perhaps they were busy talking, texting or checking updates on WeChat without looking at what was going on around them. As the number of this new “species” of human has kept rising, they have been given a new name —phubbers(低头族).

    Recently, a cartoon created by students from China Central Academy of Fine Arts put this group of people under the spotlight. In the short film, phubbers with various social identities bury themselves in their phones. A doctor plays with his cell phone while letting his patient die, a pretty woman takes selfie in front of a car accident site, and a father loses his child without knowing about it while using his mobile phone. A chain of similar events eventually leads to the destruction of the world.

    Although the ending sounds overstated, the damage phubbing can bring is real.

    Your health is the first to bear the effect and result of it. “Constantly bending your head to check your cell phone could damage your neck,” Guangming Dailyquoted doctors as saying, “the neck is like a rope that breaks after long-term stretching.” Also, staring at cell phones for long periods of time will damage your eyesight gradually, according to the report.

    But that's not all. Being a phubber could also damage your social skills and drive you away from your friends and family. At reunions with family or friends, many people tend to stick to their cell phones while others are chatting happily with each other and this creates a strange atmosphere, Beijing Evening News reported.

    It can also cost you your life. There have been lots of reports on phubbers who fell to their death, suffered accidents, and were robbed of their cell phones in broad daylight.