下列有关实验现象的描述正确的是（ ） A．木炭在氧气中燃烧，持续红热 B．铁丝在

刺激骨髓中红细胞增生

A．雌激素
B．孕激素
C．雄激素
D．促卵泡素
E．黄体生成素

By the time Bob arrives in Beijing, we have already arrived here for two days.

A．we have been staying here for two days

B．it has been for two days we have stayed here

C．it is already two days before we have arrived here

D．we will have stayed here for two days

轴流风机是常见烘干设备。

分离水溶性生物碱常用的沉淀试剂是

A．碘-碘化钾试剂

B．碘化铋钾试剂

C．磷钼酸试剂

D．苦味酸试剂

E．雷氏铵盐试剂

不能通过静脉肾盂造影检查的部位是

A．肾盏
B．肾盂
C．输尿管
D． * *
E．膀胱