哮喘持续状态
参考答案：
哮喘严重发作，经一般治疗24小时仍不能缓解者。
— Hi, Li Hua. Do you still remember the first time we met?
— Sure. You dinner with your friends in a restaurant.[ ]
A. have
B. had
C. were having
D. have had
500hPa对应的高度大约为（）
