大庆油田几次获得国家科技进步特等奖？
参考答案：三次
The murderer was brought in , with his hands ___ behind him. [ ]
A. being tied
B. having tied
C. to be tied
D. tied
影响奥氏体晶粒长大的两个最主要因素是加热温度和保温时间，并且加热温度的影响比保温时间更为明显。（）
