问题 单项选择题

对公司而言,发行不同种类的公司债券有不同的限制条件,其中有公司债券不得随便增加、债券未清偿之前股东的分红要有限制等的是(  )。

A.不动产抵押公司债

B.信用公司债

C.保证公司债

D.收益公司债

答案

参考答案:B

完形填空
完形填空。
     I have a problem with my parents: I want to wear some nail polish (指甲油) but they won't __1__ me
  to do so. They tell me that only after I have reached twenty-one can I __2__ anything for myself. This is
 so__3__ . I think nail polish is beautiful, and many of my friends wear nail polish to school. I told my
 parents about it but they still __4__ listen. How can I wait __5__ I'm
  twenty-one?                                                
                                                                                                                            Olivia, 11, China
     Hey, Olivia! If you want to wear it and your friends __6__ you about it, here is what you can do. Sit
 down with your mother in a quiet place and tell her not to start yelling (叫嚷) and saying "no" right away.
 If she does do this __7__ you tell her, say, "You might have wished to and probably got to wear it when
  you were at my __8__ ."But don't yell at her, and if she says she couldn't do it at your age either, then
 that is probably the reason __9__ she doesn't want you to do so. If you still can't wear it ... oh well, then
  don't. Don't make it worse by wearing it when they tell you not to. If your friends laugh at you, tell them
 you don't __10__ about what they say. And if they make unfriendly jokes on you, then they are not your
  true friends.
                                                                                                                             Bianca, 10, America
( ) 1. A. teach
( ) 2. A. obey
( ) 3. A. surprising
( ) 4. A. wouldn't
( ) 5. A. if   
( ) 6. A. know about
( ) 7. A. than
( ) 8. A. age  
( ) 9. A. how  
( ) 10. A. design
B. allow
B. achieve
B. exciting
B. shouldn't
B. until
B. care about
B. and
B. idea
B. why
B. study
C. advise   
C. find    
C. frustrating
C. needn't
C. because   
C. give up  
C. after  
C. school  
C. when    
C. care    
D. influence        
D. decide            
D. interesting       
D. couldn't      
D. so                
D. make fun of      
D. before            
D. point            
D. where            
D. experience        
单项选择题

许多细菌和病毒会给人类带来疾病,造成死亡,然而,人们也正是利用这类______以毒攻毒,把它注射到正常人的身体里,使人体在后天产生对某种疾病的抵抗力.这种用来注射的细菌和病毒,就是疫苗(或菌苗).疫苗的利用,可以追溯到10世纪我国宋朝时代,当时一些民间医生就已知道用天花病人防疫注射的痘痂,吹进健康人的鼻孔里,使他在患轻微的天花病过程中,获得对天花病毒的免疫力.18世纪,天花病广泛流行,夺去了无数人的生命.英国乡村医生琴纳惊异地发现,面对令人惊恐战栗的天花,挤牛奶的姑娘们却没有一个生病.这是什么原因呢他进一步研究得知,原来姑娘们在挤牛奶时,手无意中接触了牛痘的浆液,牛痘病毒就从手上细小的伤口进入人体,虽然手上出现了寥寥无几的痘疹,但姑娘们对天花病毒从此具有了免疫力,这一发现使他大受启发,在经过一系列实验后,他为一个小男孩接种了牛痘,成功地获得了预防天花的免疫效果.这是人类用科学方法免疫防病的开端.经过几个世纪的努力,人们已经研制出了多种疫苗,用来注入人体,抵抗各种疾病的袭击,有效地控制了天花、麻疹、霍乱、鼠疫、伤寒、流行性脑炎、肺结核等许多传染病的蔓延.那么.人体注射了疫苗,为什么能预防传染病呢疫苗、菌苗都是利用微生物制成的,所以为生物制品.绝大多数生物制品对人体来说,是一种大分子胶体的异体物质,人们把它称为抗原.当抗原进入人体后,它可以刺激人体内产生一种与其相应的抗体物质.抗体具有抑制和杀灭病原茵的功能,这便是人体内的免疫作用.例如种牛痘所以能预防天花,就是因为预防接种后,抗原物质作用于人的机体,除了引起体内先天性免疫增强外,还能刺激人体内产生大量抗体和免疫活性物质______转移因子、干扰素等,这样,人体对再侵入的天花病毒就具有自动获得免疫力了.

根据本文,在人体注射了疫苗后,能够预防传染病的原因不正确的一项是 ()

A.当抗原进入人体后,它可以刺激人体内产生一种与其相应的抗体物质

B.当抗原进入人体后,它不能刺激人体内产生一种与其相应的抗体物质

C.抗体具有抑制和杀灭病原菌的功能

D.预防接种后,抗原物质能增强体内先天性免疫能力