<綜合測驗>第11至15題為題組 Mystery shoppers are paid consumers who are hired to shop in stores and collect data. They are sent to a wide variety of service-based businesses， including stores， restaurants， and banks—potentially anywhere customers are served. Sometimes referred to as secret shoppers， mystery shoppers ______ regular customers to purchase items， eat in restaurants， make inquiries， or return items. (A) call for (B) pose as (C) attend to (D) engage in
