Directions: Try to identify sentences that serve specific roles in the following abstract. （摘要中共6句话，作答时只需在答案中填写1-6其中任一数字即可，不要加括号。例如，认为第一句为正确答案，即在答案处写1）Abstract:(1)The concept of happiness has been extensively studied in psychology but has received limited attention in the marketing field as the antecedent of the consumer behaviour aspects such as impulse buying and brand loyalty. (2)This research considers the effect of happiness on impulse buying and brand loyalty and examines how brand loyalty affects impulse buying. (3)The regression analysis was used to assess the assumed effects.(4)The assumption of the existence of the relationship between happiness, impulsive buying and brand loyalty was not supported, revealing that this phenomenon still requires further scientific attention. (5)Contrary to the predictions, the brand loyalty was positively related to the affective aspect of impulsive buying tendency. (6)This study contributes to the understanding of the reasons for the brand loyalty and impulse buying, where the latter is associated with negative outcomes with respect to the individual.Question 1 Which sentence provides background information?Question 2 Which sentence summarizes the main idea of the research?Question 3 Which sentence introduces the method of the study.Question 4 Which sentence sums up the result contrary to the expectation?