问题 填空题

按要求回答下列问题。

(1)石墨晶体中C-C键的键角为________。其中平均每个六边形所含的C原子数为________个。

(2)金刚石晶体中含有共价键形成的C原子环,其中最小的C环上有______个C原子。

(3)CsCl晶体中每个Cs+周围有____个Cl-,每个Cs+周围与它最近且距离相等的Cs+共有____个。

(4)白磷分子中的键角为____,分子的空间结构为____,每个P原子与____个P原子结合成共价键。若将1分子白磷中的所有p-p键打开并各插入一个氧原子,共可结合____个氧原子,若每个P原子上的孤对电子再与氧原子配位,就可以得到磷的另一种氧化物____(填分子式)。

(5)二氧化硅是一种____晶体,每个硅原子周围有____个氧原子。

(6)晶体硼的基本结构单元都是由硼原子组成的正二十面体的原子晶体。其中含有20个等边三角形和一定数目的顶角,每个顶角各有一个原子,试观察图形回答。这个基本结构单元由____个硼原子组成,共含有____个B-B键。

答案

(1)120°;2

(2)6

(3)8;6

(4)60°;正四面体;3;6;P4O10

(5)原子;4

(6)12;30

多项选择题
完形填空
完形填空。
     Whenever we hear about "the homeless,", most of us think of the Developing World. But the   1    is
that homelessness is everywhere. For example, how many of us would expect to see people living on the
streets of a   2    country like Germany?
    Kurt Muller and his wife Rita have spent eleven years making   3 for the homeless of Berlin, Germany's
capital. They first   4   one long hot summer when most Germans were   5   on holiday. Kurt and his wife
stayed at home, made sandwiches,   6   a table in the street and gave food to the homeless.
     The Mullers soon realized that food and clothing weren't    7    . "What these people also need is
warmth and   8  ," says Rita. The Mullers didn't    9  to give their phone number to the street people and
told them to phone anytime. Rita    10    there was somebody at home to answer the phone and their home was always    11 to anyone who couldn't face another night on the street.
     The couple were soon    12    all their time and money, so Kurt visited food and clothing companies
to    13    donations. Today, over thirty companies   14    donate food and other goods to the cause and
volunteers help  to  15    them to the homeless. The public also give clothes and money and a shoe producer   16  new shoes.
     Kurt and Rita receive no   17   for their hard work. " We feel like parents," says Rita, "and parents
shouldn't    18    money for helping their children. The love we get on the streets is our salary." Though Rita
admits she often gets   19   . she says she will continue with her work because she likes the feeling of having made a   20   in the world.  
( )1. A. result   
( )2. A. traditional
( )3. A. preparations
( )4. A. began     
( )5. A. asleep    
( )6. A. brought up
( )7. A. enough    
( )8. A. fame    
( )9. A. hesitate  
( )10. A. make sense
( )11. A. open  
( )12. A. costing
( )13. A. pay for
( )14. A. completely
( )15. A. advertise
( )16. A. donates
( )17. A. permission
( )18. A. borrow  
( )19. A. surprised
( )20. A. profit  
B. truth  
B. developing
B. houses  
B. met   
B. alone   
B. set up  
B. necessary
B. freedom  
B. agree    
B. found out
B. crowded
B. wasting
B. ask for
B. calmly  
B. sell  
B. produces
B. payment
B. raise  
B. excited
B. difference
C. reason   
C. typical   
C. meals     
C. called   
C. across    
C. put aside
C. helpful  
C. courage  
C. pretend  
C. make sure
C. noisy    
C. taking   
C. look into
C. regularly
C. deliver   
C. designs   
C. direction
C. save    
C. tired     
C. decision  
D. idea      
D. wealthy    
D. suggestions
D. left      
D. away      
D. gave away  
D. expensive  
D. caring    
D. intend    
D. worked out
D. near      
D. spending  
D. carry out  
D. roughly    
D. lend      
D. collects  
D. support    
D. expect    
D. amused    
D. rule