阅读下面语段，完成下列各题。

    世有伯乐，然后有千里马。千里马常有，而伯乐不常有。故虽有名马，辱于奴隶之手，骈死于槽枥之间，不以千里称也。

    马之千里者，一食或尽粟一石。食马者，不知其能千里而食也。是马也，虽有千里之能，食不饱，力不足，才美不外见，且欲与常马等不可得，安求其能千里也。

   策之不以其道，食之不能尽其材，鸣之而不能通其意，执策而临之，曰：“天下无马。”呜呼！其真无马耶？其真不知马也！

电梯为居民上下楼带来很大的便利，出于安全考虑，电梯设置了超载自动报警系统，其工作原理如图所示，电梯厢底层装有压敏电阻R₁，R₂为保护电阻．K为动触点，A、B为静触点，当出现超载情况吋，电铃将发出报警声，电梯停止运行，下列说法正确的是（　　）

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人体内主要完成物质运输功能的系统是(    )

    Today is October 4th．It's World Animal Day．Gina  and her sister Sally go to the____early．They want to do some things for the____there．In the south of the zoo，Gina finds an elephant．Its____ are kind of dirty．Gina and Sally get some____and clean them．After that they get some food for this elephant．After the elephant eats the food，the two girls take a photo with it．Then they play with it．

    This elephant is____．It can draw．It can play soccer,too．Gina and Sally like it very much．Gina and Sally play with it for a long time．They have a great time in the zoo．