裂解汽油加氢装置停车氮气置换前必须将液体物料倒空。
参考答案：对
成釉细胞瘤有以下临床表现，除了
A．男性患者占绝大多数
B．渐进性颌骨膨大
C．按之有乒乓感
D．X线可为单囊或多囊性透射影
E．肿瘤区牙齿移位、松动
--- Remember, Dad, Thomas Edison got bad grades in school, too.
--- Stay in your room until you’ve _____ the electric lamp.
A invented B discovered C made D imagined
