下列各项中属于生态系统的是：

阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空。

    Although most people believe that formal schooling is required for scientific success, a college degree is not always necessary.____excellent example of a man who won fame as a scientist ____academic(学术的) training is Vincent J. Schaefer. His formal education ended ____ two years of high school when he had to go to work in an untrained job at General Electric. Because ____ his inventive mind and his skill as a model maker, he was soon allowed to try his own experiments in the company laboratory. His natural ____ (curious) made him wonder about clouds. He developed, after many tries, a method of making clouds rain ____they would not normally do so. This method, ____ (call) seeding, has been very  ____ (help) to farmers, and ____made him win much fame.

    Schaefer believes that for people____, most of all, are interested in the world and everything in it, a college degree is unnecessary.

阅读理解

  Before you go to another country，it is a great help if you know the language and some of the customs(风俗)of the country．

    When people meet each other for the first time in Britain．they say“How do you do?”and shake hands．Usually they do not shake hands when they just meet or say goodbye．But they shake hands after they haven’t met for a long time or when they will be away from each other for a long time．

    Last year a group of German students went to England for a holiday．Their teacher told them that the English people hardly shake hands，so when they met their English friends at the station，they kept their hands behind their backs．The English students had learned the Germans shake hands as often as possible，so they put their hands in front and got ready to shake hands with them．It made both of them laugh．

“贤者举而上之、富而贵之，以为官长；不肖者抑而废之、贫而贱之，以为徒役。”这句话主要反映了战国时期的（   ）