Lots of people believe that their memory gets worse as they get older. But this doesn’t have to be  41  for you. Research shows there are some things you can do to help keep your brain active and your memory sharp as you age.  42  physical exercise and mental exercise will help your memory. Physical exercise improves circulation of the blood. This helps your brain function  43  . Keep your body active by walking, going to the gym, swimming, or riding your bike. Your brain, like your muscles, also needs  44  to stay in shape. Try to challenge yourself by doing mental exercises. Do crossword puzzles, read a lot, and play games that require  45  – games like chess. All of these mental exercises will help improve your memory. Remember, memory is like a muscle. The more you use it, the better it gets.

【Please answer questions 46-50 according to your understanding of the above passage.】 

        The brain also has its own sense organs that detect when the blood contains too much sugar or salt. After the brain gets the message that the body needs water to reduce the amount of the sugar or salt, you start to feel thirsty. That is why cookies, candy, or even very sugary soda or juice, can make you just as thirsty as salty foods.