阅读短文，根据短文内容及首字母提示，在空白处填入一个适当的单词。

People and animals live in the same world. We should keep the balance (1) b_____________ people and animals. If the balance is destroyed，there will be bad result to both people and animals. Wild animals are (2) f_____________ of people. We have to (3) p_____________ them, or there will be no wild animals in the future. Now we know that there are (4) n_____________ 2,000 nature reserves（自然保护区）in China

There is a black and white animal (5) l_____________ in China. It is always known as the national treasure（国宝）of China. Everyone knows it is called Giant panda. Now there are (6) f_____________ pandas than before. Most of them live in Sichuan and Gansu Provinces. There are also some other rare animals in China. (7) H_____________, the (8) n_____________ is becoming smaller and smaller than before. So people should try (9) t_____________ best to help these animals. They are in (10)d_____________ of disappearing from the world.

关于感应电流，下列说法中正确的是[ ]

A．只要闭合电路内有磁通量，闭合电路中就有感应电流产生

B．穿过螺线管的磁通量发生变化时，螺线管内部就一定有感应电流产生

C．线圈不闭合时，即使穿过线圈的磁通量发生变化，线圈中也没有感应电流

D．以上说法都不正确