医生认为有必要时，可以将在押人员列为三级重大安全风险对象。
参考答案：对
— Excuse me. Where is Class Three?
— _____. I'm a student in Class Three. [ ]
A. Keep waiting
B. Come this way
C. Quiet, please
D. Don't mention it.
高级耐火材料的耐火度是（）至2000°C。
A、1600
B、1770°C
C、1800
