When I was a little kid, one of my favorite things to do was going to the zoo. I have recently heard that there are debates as to whether elephants should live in zoos or should they wander around free. My position is that elephants should live in zoos for people to see.

    Many experts say that elephants have a good life living in zoos. There are 78 zoos that exhibit elephants. Most zoos are taking the necessary steps to make living conditions better for the elephants. They are doing things such as replacing hard floors with sand or dirt. This makes it easier for them to wander around. Zoos are also expanding their elephant house to give the large animals more room to go around.

    Zoos also protect endangered species. According to the World Wildlife Fund, in 2014 the total population of African elephants was around 700,000, and the Asian elephant population was around 32,000. The Asian elephants are on a path to dying out. Without zoos, they all are likely to disappear within our lifetime. The National Zoo plans to spend millions of dollars on a new Asian elephant habitat. That way, they can start their own group if the Asian elephants are gone.

    There are people who want zoos to empty all of their elephant displays. If they decide to do so, it would take the chance to see elephants up close away from people. That could change the public's favorable opinion of elephants. National Zoo director John Berry says that allowing visitors to experience the elephants up close encourages people to care about endangered species.  During one of my visits to the zoo, it was a very hot day. I was sweating a lot. Big Ben, the largest elephant on display, walked up to me and gently squirted(喷) my face with water from his trunk. Everyone was amazed at what he did. That was a very nice thing for Big Ben to do. I am sure that elephants are the nicest animals on earth. I wish all zoos would keep their elephant displays open to the public. I want all my friends to be able to experience what I did with Big Ben.

    I feel zoos should follow all the necessary steps to keep elephants in zoos. I would raise money at my school if I thought it would help to keep elephants in zoos.

鉴定骨的成分时，把骨煅烧是利用有机物容易燃烧，无机物不易燃烧的原理．实验结果：煅烧后的骨，只剩下____，它使骨具有____特性；把骨进行脱钙是利用无机物与盐酸发生化学反应，无机盐被溶解分离出来．实验结果：骨脱钙后，剩下的是____，它使骨具有____特性，可以弯曲打结．

在下面一段文字横线处补写恰当的语句，使整段文字语意完整连贯，内容贴切，逻辑严密，不超过20字。

   说服不同于说理，说理注重的是过程，      ①       ，只要能获得期待的结果，过程和手段可不考虑。好的说理要求真实、逻辑合理、论据可靠。然而，      ②      ，也不一定能起到说服的效果。如果你跟对方说的理与他的利益不符，      ③      。相比之下，说服指的是一种实际受影响的行为。非真实、逻辑谬误、论据不可靠的宣传或误导，也可以产生这样的说服效果——“依从”。

         --Yes，I do．I should go home because my flowers need         ．

世界上最早的纸币“交子”出现在我国的（   ）