支气管哮喘发作有哪些先兆症状？静脉推注氨茶碱的注意事项？

A. Configure OSPF between trigger router and black hole routes
B. Configure all edge routers with static （reserved） host route to Null0
Configure BGP beteen trigger and black hole routers
D. Configure on trigger router to advertise victim host route with commumity
E. Activate black hole by redistributing route for victim into BGP with next-hop set to the static（reserved）host route configured on edge router

A. 增强法兰
B. 防止法兰生锈
C. 密封法兰缝隙
D. 连接法兰