施工升降机司机只要有技术、责任心强，不经培训，也可上岗操作。
参考答案：错
空冷风机启动后必须保证空冷岛各排散热器端部小门以及同一排中各冷却单元的隔离门在（）位置。
—He worked out such difficult questions at a very young age.
—Oh, he _______a very smart student then [ ]
A. could have been
B. should have been
C. might have been
D. must have been
