包埋该熔模之前,须对该熔模进行清洗,清洗熔模的目的是() A. 去除熔模表面的污物、脱脂,减少熔模表面的张力 B. 使熔模表面更平整 C. 增加铸型的结固膨胀 D. 增加铸型的热膨胀 E. 以上均是 参考答案:A
第7题: [单项选择]Questions 15 to 18 are based on the passage you have just heard.What did Ethbell do when she was 68 A. She sat back and relaxed. B. She decided to retire. C. She entered university. D. She worked out a new English program. 参考答案:C 答案解析:[听力原文]15-18 After retiring from 30 years of teaching, Ethbell Pepper could easily have decide