题目内容：
根据内容回答题，When Pat Jones finished college, she decided she wanted to travel around the world and see as many foreign places as she could _51_ she was young. Pat wanted to visit Latin America first, so she got a job _52_ an English teacher in a school in BoliviA．Pat spoke a little Spanish, _53_ she was able to communicate with her students even when they didn’t know much English. A sentence she had read somewhere stuck in her mind: if you dream _54_ a foreign language, you have really mastered it. Pat repeated this sentence to her students and hoped that someday she would dream in Spanish and they would dream in English.
One day, one of her worst students came up and explained in Spanish that he had not done his homework. He had _55_ early, and had slept badly.
“What does this have to do with _56_?” Pat demanded.
“I dreamed all night, Miss, Jones, and my dream was in English!”
“In English” Pat was very surprised, since he was such a bad students. She was _57_ secretly jealous. Her dreams were still not in Spanish. But she encouraged her young student, “Well, tell me about your dream.”
“All the people in my dream _58_ English,” the student said, “And all the signs were in English. All the newspapers and magazines and all the TV programs were in English.”
“But that’s wonderful,” said Pat, “What did all the people say to you?”
“I’m _59_, Miss Jones. that’s _60_ I slept so badly. I didn’t understand a word they say,It was a nightmare!”
A．as
B．while
C．if
D．since
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