关于速度和加速度的关系，下列说法中正确的是（） A.速度变化较多的运动，加速度必较大

     On the first day of my school life in the USA, I showed a great interest in my marketing class. My
teacher, Mrs. Tolman, suggested I  __1__  a national marketing club called DECA attracting many
students with talent and interest in  __2__. So I did.    
     The first  __3__  was to raise money for the marketing competition later in the year by selling
candles. Mrs. Tolman said the competition was due in a week and that 40 percent of the  __4__ would
go into my personal account.    
     At the beginning, I tried to sell some candles to my host mom. She said that if I could   __5__  
confidence and do a wonderful sales presentation, she would certainly buy some. I started my  __6__    
with a firm handshake. Then I introduced all the different kinds of candles and the special sales I could
offer and  __7__  her that our candles were the best choices for gifts and home decorations. Finally
she bought three candles.    
     Greatly  __8__  I decided to sell my candles around the neighborhood. On Saturday morning, with
great courage, I knocked at the door of my first potential  __9__.    
     "I'm a student at Skyline High School and we are __10__  money for DECA. I'm trying to sell..."  
      "Not today, sorry, "  the man interrupted me and __11__  the door.    
     Embarrassed, I walked away and said to myself the __12__ thing that might happen was being
refused like that again. I couldn't even count how many times I was __13__  with reasons like "Not
today" , "I don't have any __14__ money right now" or "I just bought some". __15__, I had to continue
with the day. __16__, a woman kindly bought nearly  $ 60 worth of candles. I couldn't even hide my 
__17__  and said "Thank you very much" to her with a bow.    
     After a  __18__  hard work, I turned in my $408 worth of sales of candles, which gave me $163 in
my own account. I was __19__  to find out I was the second highest seller in all classes.    
     It was the first time that I had worked as a sales person. This experience let me know that __20__ 
difficulties was only wasting time and a barrier in my way to success.