如图直角三角形ABC中，$\left|CA\right|=\left|CB\right|$，$\left|AB\right|=3$，点E，F分别在CA，CB上，且$EF\parallel AB$，$AE=\sqrt{2}$，则$\overrightarrow{AF}·\overrightarrow{BE}=$（   ）

下表中所列的是12月22日甲、乙、丙、丁四地的白昼时间，根据表中数据完成下列问题。

根据短文理解，完成下列各题。
    Recent research from the Pew Internet Project suggests that 90% of Americans aged from 12 to 17 use the Internet, and 51% of those teens use social networks. However, there are many possible problems with social networking sites and the teenagers who use them.
    Apart from the social advantages, social networking sites can be used to record school research, develop artistic talents and experiment with other forms of subject creation. They provide a way to communicate with others who share the same interests and to get helpful advice on ongoing projects.
    Along with these advantages come some dangers. For example, most social networking sites are open to all, especially MySpace, which is the most popular social network among teens in America. It means that they could be put in unpleasant and frightening situations.
    A greater danger is that teens may become objects of the people with secret purposes. The secrecy of some social networking sites makes it easy for dangerous people to find young teens and invite them into dangerous conversations. It's easy for them to pretend as teens and draw children into dangerous real-world communication as well. Then further hurt might be on its way.
    Another danger is identity stealing, which can happen when teens share too much information about their names, dates of birth and locations.
    Therefore, it's very important to make sure teens are safe when they use social networks.
    Many of the same rules that work for online chat work for these sites:
    ※ Don't use your real name.
    ※ Don't give out personal information to people you don’t know. A last name and a town are enough for a bad guy to find where you are.
    ※ Don't believe that people are who they say to be.
    ※ Immediately end any communication that makes you uncomfortable and report it to a parent.
   Only if you are sure of your safety, can you enjoy the fun brought by social networking. Besides, trying to deal with all problems on your own can lead to terrible results. Remember, asking your parents or school officials for help doesn’t mean you are unable to do anything but wiser than many others.                       
                    

下列不能说明生物是适应环境的是    (    )

《史记》记载，秦孝公死后，守旧的贵族诬告商鞅“谋反”，商鞅也因此遭遇了车裂的命运。下列选项最有可能导致商鞍悲剧的是（  ）