Once there was a prisoner who was jailed in a dark prison which he thought was a great fortress（堡垒）．The cell was dark and wet． There was a tiny window with bars on it． The rest of the cell was so dark that he could not see the other three walls． The only wall he could make out was the wall with the window in it． The only light the room received was from this window． Once in a while the prisoner would manage to climb up to the window and look out on the world outside． If he stretched and looked， he could see a little bit of the life-giving sun out there．
For the first five years in that prison the prisoner stayed in the tiny place of light thrown in through the window． He never tried to go past the edge of the little square of light． But then he became restless． The prisoner started to move a little bit at a time deeper into the darkness of his prison cell． He moved a few inches a day． After what seemed like a year he found the left-hand wall of the cell． It took him much less time to find the right-hand wall as he was becoming more confident．
Then he began to search for the wall opposite the window． As he went deeper and deeper into the darkness of the cell he thought of turning back． But his curiosity drove him forward． In the darkness of his cell he found the back wall had a door． And the door was open!
The door had always been open， and it led to a passage， which led him out of the dark prison into freedom and the life-giving sun． His imprisonment（监禁）had all been his mind．



Why did the prisoner NOT think of running away from the cell？ ______

A. Because the cell was very dark and he could see nothing．
B. Because the cell was so well-guarded and he could see no way to escape．
C. Because he had thought there was no possibility to escape from the cell．
D. Because he was afraid of getting lost if he walked out the cell．

What did the prisoner do during the first five years？ ______

A. He searched for ways to get out．
B. He stayed where the light shone．
C. He did nothing but blame himself．
D. He thought about where the other three walls were．

Which of the following statements is TRUE？ ______

A. The prisoner couldn't see even a little of the sun in the dark cell．
B. The prisoner was certain that there was a door before finding it．
C. The prisoner found the left-hand wall of the cell in a short time．
D. The prisoner thought of giving up looking for the back wall．