启动引、送、一次、密封等离心风机时，均应先关闭（），对于轴流风机则应打开（）。
参考答案：入口挡板；出口挡板
It's reported that CCTV 3 _____ the concert to be held this weekend. [ ]
A. will cover live
B. would cover live
C. will be covered live
D. would be cover live
鱼苗池清塘后，继轮虫、裸腹蚤繁殖高峰期后，常出现大量（）
A.隆线蚤
B.大型蚤
C.长刺蚤
D.剑水蚤
