In example 8, Kerry gives reason to buyer D that their quality is better so the price is much higher. In the following utterance, speaker D want to persuade the seller to cut down price, however, he firstly agrees to Kerry that their material is better by saying "yes”. Under such circumstance, seek agreement as the positive politeness strategy may make the outcome more efficiently. Speaker D in example 9 also seeks agreement with H that they will have a long cooperation in the future. Such expression may add the sincerity and cooperation between each other,avoiding threatening the face of both S and H.