问题 填空题

如图所示,质量为M、倾角为θ的斜面体静止在粗糙的水平面上,质量为m的物块放在斜面上恰好能沿斜面匀速下滑,则物块与斜面间的动摩擦因数μ为__________,此时地面受到的压力大小为_________。

答案

tanθ,(m+M)g

单项选择题
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     I believe in miracles because I've seen so many of them.One day,a patient was referred to me who was
one hundred and two years old."There's a    1    in my upper jaw,"she said."I told my own dentist it's
nothing,but he     2      I come to see you."
    Her eighty-year-old son accompanied her.He would     3     to add something,but she stopped him.She
wanted to tell everything hereslf.I found a large cancer that spread over much of the    4     of her mouth.A
careful examination later     5    that it was a particularly bad sort of cancer.
     During her next appointment,I explained to her the     6    of the problem.She clasped my hand in hers
and said,"I know you're worried about me,but I'm just    7    ."
    I thought otherwise.After considerable     8    on my part,and kindness on her part because she wanted
to    9    me,she agreed to have me refer her to a cancer surgeon.She saw him,but as I expected,   10    
treatment.About six months later she retarned to my office,still energetic and          11     
    "How are you?"I asked.
     "I'm just fine,honey,"she responded     12   high spirits."When can I get started on fixing my dentures(假牙)?"
Surprised to see her at all,I answered    13     ,"Let me take a look in your mouth and we'll see about it."
    I couldn't believe my eyes.The cancer that had     14      nearly the entire roof of her mouth was gone-only onesmall area of redness     15     .
    I had read of such things happening,but had     16   seen them with my own eyes.That was my first
miracle.
    Since then I've seen many others,because they keep getting      17    to see.In fact,miracles are daily
events for me now.And people are a miracle,      18     through them we have a chance to know ourselves
and to    19     the miracles of one another.
    Since my first miracle,I've come to understand that the time and place for a miracle is    20    we choose
to find it.

( )1.A.pain    
( )2.A.declared  
( )3.A.manage    
( )4.A.corner    
( )5.A.considered
( )6.A.possibility
( )7.A.old    
( )8.A.permission
( )9.A.persuade  
( )10.A.received
( )11.A.healthy
( )12.A.to  
( )13.A.worriedly
( )14.A.reached
( )15.A.left  
( )16.A.ever  
( )17.A.easier
( )18.A.for  
( )19.A.read  
( )20.A.whatever
B.wound      
B.promised  
B.continue  
B.roof    
B.convinced  
B.seriousness   
B.sick    
B.effort  
B.encourage   
B.provided  
B.elegant    
B.in    
B.patiently   
B.covered    
B.faded    
B.also    
B.rarer    
B.so      
B.keep     
B.wherever   
C.cut      
C.insisted  
C.keep    
C.bottom    
C.confirmed  
C.importance  
C.glad     
C.approval  
C.please  
C.refused    
C.optimistic   
C.with    
C.confusedly  
C.spread    
C.expanded  
C.never     
C.happier    
C.yet      
C.see      
C.whoever    
D.cancer          
D.suspected        
D.attempt          
D.surface          
D.concluded        
D.resolution      
D.fine            
D.support          
D.astonish        
D.required        
D.humorous        
D.by              
D.confidently      
D.grown            
D.remained        
D.already          
D.closer          
D.or              
D.make            
D.whichever