[单选题]It is regulated by company that __ minutes before takeoff clearance the captain, maintenance agent and flight dispatcher must ensure there is no ice, frost or snow, and flight control system is normally operational. A.5 B.10 C.15 D.20
第23题: [单项选择]下列近代中国与西方列强签订的不平等条约中规定开放通商口岸数量最多的是:() A. 《南京条约》 B. 《天津条约》 C. 《马关条约》 D. 《北京条约》 参考答案:B 答案解析:《天津条约》开放牛庄、登州、台南、淡水、潮州、琼州、汉口、九江、南京、镇江十处为通商口岸,是我国近代开放通商口岸最多的不平等条约。故选B。A项五处通商;C项四处通商;D项一处,就是天津开放为通商口岸。
第31题: [多项选择]Which two states are the8194;port states when RSTP has converged?() A. blocking B. learning C. disabled D. forwarding E. listening 参考答案:A,D