1.　　　 偿还债务 pay back the debt

1.　 发生　　 take place

60.把……翻译成　 translate…into

Unit 19 some phrases

59.从中学习　　 learn from

58.知道，追踪　 keep track of

57.犯错误　　　 make mistakes

56.被用来学英语 be sued to study English

55.把……比作　 compare… to…

54.科学的暗喻　 scientific metaphors

53.将来　　 in the future