窑慢转转速为（）r/min，转1/4圈时间为（），雨、雪天气时应根据实际情况，应（）慢转时间间隔
参考答案：0.191；79S；减半
23. --- Where ____ the recorder? I can’t see it anywhere.
--- I ____ it right here. But now it’s gone.
did you put; have set up B. have you put; put
C. had you put; was putting D. were you putting; have put
矿石硬度的表示方法有（）种。
A．1
B．2
C．3
