在XJM-4型浮选机中，定子与转子之间的径向间距要适中，一般在15mm较合适。
参考答案：错
I'm afraid Mr. Harding _____ see you now. He's busy. [ ]
A. can't
B. mustn't
C. shouldn't
D. needn't
18F-FDG心肌代谢显像为何需葡萄糖负荷
