makes ice melt(融化). The ice round the string will begin to melt. But when it melts, it will lose heat. The cold ice cube will make the salt water freeze again.

　　After a minute or two you may raise the piece of string and with it you will raise your piece of ice!This experiment can be very useful to you. If, for example, there is ice near the door of your house, you must use very much salt to melt all the ice. If you don't put enough salt, the water will freeze again.

46. We must use _______ when we carry out this experiment.

A. fridge B. some food C. a table D. some salt

47. How long will it take to carry out this experiment?

A. More than three minutes. B. Five minutes or so.

C. Only one minute or two. D. About ten minutes.

48. What is the task of this experiment?

A. Put the ice cube into the glass of water with the help of the string.

B. Take out the ice cube in the glass of water with the help of the string.

C. Take out the ice cube in the glass of water with your fingers.

D. Put some salt on the ice cube and then put the string across it.

49. How many things at least are used in this experiment?

A. Three. B. Four. C. Six. D. Seven.

50. We can learn something about _______ from the passage.

A. Physics B. biology C. chemistry D. maths

D

There is a wonderful story about a young girl who had no family and no one to love her.

One day, feeling very sad and lonely, she was walking through a grassland when she noticed a small butterfly caught in a thorn（荆棘）bush. The young girl carefully released the Butterfly. Instead of flying away, the little butterfly changed into a beautiful fairy. The young girl rubbed her eyes in disbelief.

"For your wonderful kindness," the good fairy said to the girl,"I will give you any wish you would like." The little girl thought for a moment and then replied,"I want to be happy."

The fairy leaned toward her and whispered in her ear. Then the fairy disappeared.

As the little girl grew up, there was no one in the land as happy as she. Everyone asked her secret of happiness .She would only smile and answer,"The secret of my happiness is that I listened to a good fairy when I was a little girl."

When she was very old and on her deathbed， the neighbors all gathered around her，that her unbelievable secret of happiness would die with her."Tell us, please," they begged,"Tell us what the good fairy said." The lovely old woman simply smiled and said,"She told me that everyone, no matter how secure they seemed,no matter how old or young, how rich or poor, had need of me."

51. ______ the girl felt sad and lonely.

A.There were many friends but

B. There was nobody to love her so

C. There was nothing to do