有关腰椎间盘突出症非手术治疗占（）。
A.50％
B.60％
C.80％
D.70％
E.90％
参考答案：C
— May I go out and play, Mum?
— No, you ____. You've got a lot of work to do. [ ]
A. needn't
B. mustn't
C. wouldn't
D. won't
根据《环境空气质量标准))(GB 3095—1996)的规定，PM10的小时平均二级标准限值为 ( )。
A．4 mg/m3
B．6 mg/m3
C．8 mg/m3
D．10 mg/m3
