工程液体电介质击穿是因电场作用下产生气泡，由气泡内的气体放电引起。
参考答案：对
The current market price of National Tire (NT) is $ 35. Fran Wilson writes 6-month put options on NT with strike price $ 30, coveting 400 shares (i. e. 4 contracts), for which she receives a total premium of $1200. What is the expiration day value of Fran’s written put position, if NT is priced at $ 25 at expiration（）
A. -$ 2000.
B. -$ 800.
C. $ 2000.
COPD急性加重（AECOPD）最新分期第一级为（）。
A.轻/中度
B.轻度
C.中度
D.重度
