果蔬汁

患者，男性，52岁。误吞鱼头骨后吞咽疼痛8小时，在当地医院就诊，X--线照片发现食管中段有不透光的阴影，由于当地医院条件有限，仅给予抗炎、对症和支持治疗两天，症状无明显缓解，且出现背部及胸骨后疼痛，多次呕吐，呕吐物仅为唾液样物，其中两次带有少许鲜血，于是转入我院治疗。

如果位于主动脉弓，且异物随动脉搏动而动、并伴有搏动性出血，手术时应注意的是（）。

A.应选择适当型号的食管镜取出异物

B.取异物时应尽量将异物拉入食管镜内，然后将食管镜与钳子一并取出

C.为了避免食管及大血管损伤，应将异物推入胃内，让其自行排出

D.立即胸外科开胸探查取异物，并及时修复动脉

E.可暂时观察，但要加强支持治疗

铝热反应”的化学方程式为：2Al+ Fe₂O₃Al₂O₃+ 2Fe。某同学对“铝热反应”的现象有这样的描述：“反应放出大量的热，并发出耀眼的光芒”．“纸漏斗的下部被烧穿，有熔融物落入沙中”。查阅《化学手册》知，Al、Al₂O₃、Fe、Fe₂O₃熔点、沸点数据如下

（1）该同学推测，铝热反应所得到的熔融物应是铁铝合金。这种推测有一定的道理，理由是：________________________________

（2）设计一个简单的实验方案，证明上述所得的块状熔融物中含有金属铝。该实验所用试剂是_________________，当观察到__________现象时，说明熔融物中含有金属铝。

（3）实验室溶解该熔融物，最好选用下列试剂中的_____________（填序号）。

A．浓硫酸 B．稀硫酸 C．稀硝酸 D．氢氧化钠溶液

数据库保护分为：安全性控制、【 】、并发性控制和数据的恢复。

Ranch. It was near Los Angeles in CaliforniA. A few years later Hollywood was one of the famous places in the world. At the beginning of the 20th century there was a big farm called Hollywood. From the 1910’s to the 1950’s, Hollywood was the film center of the world.
Every family knew the names of its film stars—Charlie Chaplin, Greta Garbo, Bergman and hundreds more.
The reason why people went to Hollywood to make films was the sun. At first, people made films in New York on the east coast of the United States.
But then they heard about Los Angeles, where there are 350 days of the sun every year. As they made all the films by sunlight, the west coast was a much better place to work. Also near Hollywood you can find mountains and sea and desert. They did not have to travel far to make any kind of film.
When TV became popular, Hollywood started making films for television. Then in the 1970’s they discovered people still went to the cinema to see big expensive films. Nowadays they are still making films in Hollywood and people see them all over the world.

Which statement is true

A．The west coast was a better place to make films.
B．There are no mountains near Hollywood.
C．People no longer went to the cinema after television became popular.
D．Hollywood began to make films for television after the First World War.