第21题: [单项选择]Questions 19 to 22 are based on the conversation you have just heard.A. They attend a house-sitter’s party. B. They check a house-sitter’s references. C. They interview a house-sitter’s friends. D. They look at a house-sitter’s transcripts. 参考答案:B 答案解析:[解析] 22. How do house owners determine the reliability of a house-sitter