锅炉停运后，空予器应保持运行至其入口烟温小于（）℃后才能停止。
参考答案：204
He is a student at Oxford University, _____ for a degree in computer science. [ ]
A. studied
B. studying
C. to have studied
D. to be studying
有五个连续偶数，已知第三个数比第一个数与第五个数之和多18，则这五个偶数之和是（）。
A．210
B．180
C．150
D．100
