A：badly
B：worst
C：well
D：best
The crocodile is very dangerous but we can't harm it, because it belongs to the ____(danger) species and is facing up to dying out and needs protection.
分解因式：a2﹣b2﹣2b﹣1=____ ．
《使至塞上》尾联用典故流露了向往建功立业的心情。这个典故隐含在____两个字中。
