A:物种多样性
B:遗传多样性
C:环境多样性
D:生态系统多样性
下列不属于造成环境危机的原因是( )
近现代湘籍著名文学家丁玲的代表作是( )
It is often the case ______anything is possible for those who hang on to hope.
下图漫画《精神大餐》形象地说明了( )