根据句意和汉语注释，写出单词的正确形式。

1. When the doctor came, the victim has already stopped _______ (呼吸).

2. _______  (立即), the enemy disappeared on the early foggy morning.

3. It's not surprising to see so many _______ (推销员) in such a big electrical shop in China.

4. As we know, air _______ (污染) might cause many serious diseases.

蜂鸟：鸵鸟( )

A．马尔马拉海：珊瑚海

B．燕子：鸟类

C．人生：智慧

D．代数：数学