问题 单项选择题

不锈钢管焊接一般采用手工电弧焊及氪弧焊,下列关于其焊接的说法不正确的是( )。

A.为确保内壁焊接成型平整光滑,薄壁管采用全钨极氩弧焊
B.焊接材料应与母材化学成分相近,应保证焊缝金属性能和品间腐蚀性不低于母材
C.不锈钢与碳素钢、低合金钢或耐热钢间的异种钢材焊接,宜选用A302、A307焊条
D.对不锈钢复合钢材的焊接,不应选用过渡层焊条

答案

参考答案:D

解析: 不锈钢管焊接一般采用手工电弧焊及氩弧焊,对不锈钢复合钢材的焊接,应选用过渡层焊条。

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     As we know, it is important for us to learn English. But do you think it is difficult to learn English?
And  1  do you learn English? This week we asked students at Huamgmei Shiyan Middle School about
the best ways  2  more English.  3 what Li Mei said.
     Last year my English class was difficult. First of all,  it wasn't  4  for me to understand the teacher
when she talked. To begin with, she spoke  5  quickly for me to understand every word. Later on, I know
that it doesn't  6  if you don't understand every word. I was also afraid  7  in class, because I thought my
classmates might  8  me. I couldn't always make a complete sentence,   9 . Then I started to watch
English-language TV. It helped  10 . I think that doing lots of listening practice is one of the secrets of  11  
a good language learner. Another thing that I found very difficult was English  12  . So I decided  13  a lot
of grammar notes in every class. Then I started to write my own original sentences using the grammar I was
learning. It's amazing  14  this helped. Now I am enjoying learning English and I got  15  A this term. My
teacher is very impressed.
( )1. A. what      
(     )2. A. to learn  
( )3. A. It’s     
( )4. A. boring    
( )5. A. so        
( )6. A. mind      
( )7. A. to speak  
( )8. A. smile at  
( )9. A. too       
( )10. A. very much
( )11. A. become   
( )12. A. words    
( )13. A. to do    
( )14. A. how many 
( )15. A. the      
B. why       
B. for learn 
B. There’s  
B. difficult 
B. very      
B. matter    
B. of speak  
B. help      
B. also      
B. a lot     
B. became    
B. texts     
B. doing     
B. how often 
B. an        
C. how            
C. to learning 
C. That’s       
C. easy       
C. too            
C. help          
C. for speak     
C. hit         
C. either       
C. so many    
C. becomes       
C. grammar      
C. to take       
C. how long      
C. a           
D. when        
D. for learning
D. Here’s     
D. exciting    
D. quite       
D. work        
D. for speaking
D. laugh at    
D. neither     
D. lots of     
D. becoming    
D. sentences   
D. making      
D. how much    
D. this        
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