Last summer Utpal Dholakia of Rice University interviewed 150 businesses that had done Groupon promotions.

去年夏天，赖斯大学的Utpal Dholakia访问了150家做过团宝促销活动的商户。

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Just remember not to let your coupons expire--according to a recent study by Rice professor Utpal Dholakia, about one-fifth of all Groupon coupons lapse before their owners get a chance to use them, and one-third of vendors report that the promotions are unprofitable.

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