绝热工程中，绝热结构分保温和保冷两种结构形成。其中( )是保冷的绝热结构应增加的。
A．防腐层
B．保温层
C．保护层
D．防潮隔气层
参考答案：D
—I called you at 6 o'clock yesterday evening, but nobody answered.
— I'm sorry. I my friend download the movie Kung Fu PandaⅡwhen the telephone rang,
A. would help B. helped C. was helping
产科麻醉的原则是()
A．确保母子安全
B．满足手术要求
C．防止呕吐误吸
D．简单、迅速
E．防止术后并发症
