41. According to the passage, some doctors believe it is true that (   ). 

• A、you are healthy if cold-water swimming turns your skin color blue
  
  

• B、cold-water swimming causes more heart attacks in summer than in winter
  
  

• C、cold-water swimming can make the body temperature dangerously high
  
  

• D、Polar Bears are bears swimming in freezing water
  
  

45. Which of the following is close to the word"aided"?

• A、Demanded.
  
  

• B、Helped.
  
  

• C、Caught. 
  
  

• D、Protected. 
  
  

53. (    )