日食只可能发生在农历的什么日？

临床常见诊断失误的原因有（）

A.医学知识不足

B.先入为主、主观臆断

C.病史资料不完整、不确切

D.观察不细致或检查结果误差较大

E.缺乏临床经验

氧气管道输送干燥氧气时，( )。

A．应有不小于0.001的坡度

B．应有不小于0.002的坡度

C．应有不小于0.003的坡度

D．可以水平安装不设坡度

小明和小刚住同一栋楼，小明说：“我和小刚是上下楼。”小刚住四楼，小明可能住在（    ）楼或（    ）楼。

阅读理解。

     Guangzhou (Xinhua)-12 people were killed and 20 injured early yesterday morning when they jumped

from a burning train car into the path of an oncoming goods train in Southern China. When No. 247

Wuchang-Guangzhou passenger train was passing the Dayaoshan Tunnel in Guangdong Province, South

China at 00:17 yesterday, a fire caused by passengers' smoking broke out on No. 17 car. They wanted to

extinguish fire. As the train stopped some frightened passengers jumped from windows. 12 people were

crushed to death and 20 others injured by a northward passing goods train (No. 1766).

1. In which direction did the passenger train travel? [ ]

A. Northward.

B. Southward.

C. Eastward.

D. Westward.

2. When did the accident happen? [ ]

A. At 00:17 am.

B. At 00:17 pm.

C. At seventeen past one.

D. At seventeen to one.

3. Where did the accident happen? [ ]

A. In Wuchang.

B. In Guangzhou.

C. In Hubei.

D. In Guangdong.

4. What was the cause of the fire? [ ]

A. A heavy rain.

B. High temperature.

C. Carelessness.

D. Fear.

利用激光器使工作物质受激而产生一种单色性高、方向性强及亮度高的光束通过聚焦后集中成一小斑点，聚焦后光束功率( )极高。

A．能量

B．密度

C．值

D．效率