【正确答案】正确答案：Adjacency pair is a sequence of two related utterances by two different speakers. The second utterance is always a response to the first. It has five properties: ① Adjacency pairs consist of two utterances, a first part and a second part. ② The two parts are spoken by different speakers. ③ The first and second parts belong to specific types, for example, question and answer, or greeting and greeting. ④ The form and content of the second part depends on the type of the first part. ⑤ Given that a speaker has produced a first part, the second part is relevant and expectable as the next utterance.