现在很多公交车上都用上了“非接触式”IC卡，人们上车后用刷卡代替买票，方便了乘客。这种卡应用了物理学上的电磁感应原理，你知道电磁感应现象是哪个国家的科学家最早发现的吗(   )

根据短文理解，完成下了各题。

Dear Tom,

    I go on a trip to Beijing with my father Rick. On the first day, we visit (参观) the Palace Museum. It is in the centre of Beijing. There are many rooms in it. You can see “No photos!” in some places. If so, you need to follow the instructions (指示). On the second day, we visit the Summer Palace. It's great fun to boat there. I can swim, so I'm not afraid of water. Tomorrow we will go to the Great Wall.

I also make a new friend Tony who comes from Australia. When he leaves, he gives me his e-mail address and telephone number. After the six-day trip, we can go back to New York by plane. I hope to see you soon.

Bill

有“绿色水库”之称的生态系统是（   ）。