以下指标中哪项可用来描述计量资料的离散程度
A．极差B．中位数C．均数D．几何均数
参考答案：A
When Alice came to life, she did not know how long she ________ there.[ ]
A. had been lying
B. has been lying
C. was lying
D. has lain
关于腰椎间盘突出症的预防，下列哪些措施是正确的
A．避免长期久坐
B．坚持弯腰训练
C．加强腰背肌锻炼
D．使用腰围
E．定期行理疗、推拿、按摩
