牙周炎的组织破坏特点()
A．持续性破坏
B．长时间静止、短时间破坏
C．长时间破坏、短时间静止
D．进行性破坏
E．渐进性破坏
参考答案：B
Don't try to persuade your boss; he won't have the _____ of employing me-a fresh student. [ ]
A. intention
B. attention
C. sense
D. attraction
什么情况下，循环风机应立即停车？
