如何用刚性固定法减少分段焊接变形？

最常见的两种癌胚胎抗原是________和_______。

阅读理解。

     Now let's come to the Bolshoi Theater (莫斯科大剧院) near the center of Moscow. The inside of the

theater is as brightly golden (金色的) as it was before 1917, but the audience (观众) has changed. Many

of the men are without ties (领带) and the women are wearing dark clothes. In the nineteenth century this

was Moscow's great opera house.

     "Bolshoi" means"big", and the theater can hold 4 000 persons. Culture has always been important to

Russians. That's why through all these years they have been trying to maintain (一直保持) arts, like ballet,

fine opera (歌剧) and plays.

      The government gives the theater 12 000 000 dollars each year. Even the New York Metropolitan Opera

(纽约大都会歌剧院) can only get half of the money. The Bolshoi is very large, and has its own factories

even. About three thousand people work in the theater and 250 ballet dancers are working here and they get

the highest pay.

根据短文内容回答下列问题.

1. Where is the Bolshoi Theater?

________________________________________________________________________

2. What does"Bolshoi" mean?

________________________________________________________________________

3. How many persons can the Bolshoi Theater hold?

_________________________________________________________________________

4. Which theater gets more money from the government, the Bolshoi Theater or the

    New York Metropolitan Opera?

_________________________________________________________________________

5. In the past what kind of people often went to the Bolshoi Theater, the rich people or the poor people?

_________________________________________________________________________

儿童预防接种的目的在于（　　）

A．控制传染源

B．切断传播途径

C．保护易感人群

D．三种说法都正确

卤代烃（R－X）在醚类溶剂中与Mg反应可制得格氏试剂，格氏试剂在有机合成方面用途广泛。

已知： 

（R表示烃基，R′和R″表示烃基或氢）

某有机物A有如下转化：

试回答下列问题：

（1）B→A的反应条件为__________________________，B→C的反应类型是_______________。

（2）G的结构简式是_______________________________。

（3）H中所含官能团的名称是________________________________________。

（4）写出一种满足下列条件的物质H的同分异构体的结构简式 ____________________________

①能发生银镜反应；②有三种不同氢原子；③含有最多的甲基

（5）聚苯乙烯（PS）由苯乙烯（ ）聚合而成，是一种多功能塑料，广泛应用于食品包装，机器设备等许多日常生活领域中。写出以 D和苯为主要原料制备苯乙烯（）的合成路线流程图，无机试剂任选。

（合成路线常用表示方法为：AB ……目标产物）

在保险的各个种类中，最有利于进行团体保险的险种是( )。

A．意外伤害保险 B．财产保险
C．人身保险
D．健康保险