什么是厌氧氨氧化反应？
参考答案：
无氧条件下氨被氧化的反应。
__________ outside in the street, the man was sent to hospital at once. [ ]
A. Found lying and dying fast
B. Found lying and almost died
C. To be found dying
D. Finding dead
发动机工作时，一个活塞冲程相当于曲轴旋转（）。
A、120°
B、90°
C、180°
D、360°
