C. Pain can be caused in many different ways.

D. Pain is an automatic response to bodily injury.

52. The author implies that the reason why the gate control was “amazing” was

that it A. offered an extremely new and original explanation

B. was just opposite to people’s everyday experiences

C. was grounded in an ridiculous logic

D. was so sensible it should have been proposed centuries before

53. The author refers to ―chronic back pain‖ as an example of something that

is A. costly, because it troubles millions of people

B. puzzling, because it sometimes has no obvious cause

C. disappointing, because it does not improve with treatment

D. worrying, because it lies beyond the reach of medicine

54. The last sentence of the passage serves mainly to express that

A. scientific judgments are difficult to understand

B. theoretical investigations are generally useless

C. researchers still have a long way to go before the puzzle is made clear

D. there is always something puzzling at the heart of science

D

Pete Richards was the loneliest man in town on the day that little Jean Grace opened the door of his shop.

Pete's grandfather had owned the shop until his death. Then the shop became Pete's. The front window was full of beautiful old things: jewelry of a hundred years ago, gold and silver boxes, carved figures from China and Japan and other nations.

On this winter afternoon, a child stood there, her face close to the window. With large and serious eyes, she studied each piece in the window. Then, looking pleased, she stepped back from the window and went into the shop. Pete himself stood behind the counter. His eyes were cold as he looked at the small girl. ―Please,‖ she began, ―would you let me look at the pretty string of blue beads in the window?‖ Pete took the string of blue beads from the window. The beads were beautiful against his hand as he held the necklace up for her to see.

―They are just right,‖ said the child as though she were alone with the beads. ―Will you wrap them up in pretty paper for me, please? I've been looking for a really wonderful Christmas present for my sister.‖

―How much money do you have?‖ asked Pete.

She put a handful of pennies on the counter. ―This is all I have,‖ she explained simply. ―I've been saving the money for my sister's present.‖

Pete looked at her, his eyes thoughtful. Then he carefully closed his hand over the price mark on the necklace so that she could not see it. How could he tell her the price? The happy look in her big blue eyes struck him like the pain of an old wound.

―Just a minute,‖ he said and went to the back of the shop. ―What's your name?‖ he called out. He was very busy about something.