连续操作设备中物料性质不随时间而变化，多为稳态操作。

等腰三角形ABC，其中AB=8cm，周长为20cm，则这个等腰三角形的腰长是 [ ]

A、8cm

B、4cm

C、6cm

D、6cm或8cm

My cousin Li Ming is a senior three student, who devoted himself to his lessons every day. Last Saturday, as usual, he went to several class. In the evening, he continued to study at home until deeply into the night. He was too sleepy and tired that he couldn’t work effectively. In Sunday morning, he was about to do his lessons while his father came up and advised him to take a break. Soon they came up a good idea. They decided to go cycling in the countryside. Li Ming enjoyed himself competing and chatting with his father and felt relaxing in the open air. On Monday, Li Ming was energetic and active in class. He spent a whole day in the country, and Li Ming said what he had done was worth.

执业医师的合法处方权（　）

A．大学毕业后即取得

B．实习一年后即取得

C．医师资格考试合格后取得

D．在经注册的执业地点取得

E．到任何聘用单位就有处方权

有爆炸危险厂房的平面布置，应注意（）。

A.有爆炸危险的甲、乙类生产部位，布置在单层厂房靠外墙的泄压设施或多层厂房顶层靠外墙的泄压设施附近

B.有爆炸危险的设备避开厂房的梁、柱等主要承重构件布置

C.门斗的隔墙采用耐火极限不低于3.0h的防火隔墙

D.办公室、休息室必须贴邻本厂房设置时，建筑耐火等级不得低于二级，并采用耐火极限不低3.0h的非燃烧体防护墙隔开和设置直通室外或疏散楼梯的安全出口

E.排除有燃烧或爆炸危险气体、蒸气和粉尘的排风系统的排风设备不得布置在地下或半地下建筑（室）内

如图所示，一个小球从地面竖直上抛。已知小球两次经过一个较低点A的时间间隔为T_A，两次经过较高点B的时间间隔为T_B，重力加速度为g，则A、B两点间的距离（）

A.

B.

C.

D.