亚急性硬化性全脑炎由下列哪个疾病引起（）
A.风疹
B.麻疹
C.幼儿急疹
D.水痘
E.疱疹病毒脑炎
参考答案：B
---- Flight 551 for Dallas ________. I must be off now.
------Have a pleasant trip then.
A．is being announced
B．has announced
C．was announcing
D．had been announced
斜道区布置着数量众多的通道有（）
A.斜道
B.水平砖煤气道
C.烟道
D.垂直砖煤气道
