降低直接还原度的方法有哪些?
参考答案:
降低直接还原度的方法有:
①改善铁矿石的还原度;
②延长煤气与矿石的接触时间;
③扩大高炉的中部区域;
④喷吹含H2的燃料。
It was____back home after the experiment.[ ]
A. not until midnight did he go
B. until midnight that he didn't go
C. not until midnight that he went
D. until midnight when he didn't go
当时钟前面板上无显示,飞机上电网供电正常,则表明:
A、时钟的显示有问题,但还在计时
B、时钟内部有故障
C、无GPS信号输入
D、不确定