这家超市在洗发水上推出了买一送一的促销活动。

The supermarket is offering a ___buy-one-get-one-free promotion on shampoos this weekend.

参加这个课程真是买一送一：你不仅能学到技能，还能结交行业人脉。

Enrolling in this course is a ___buy-one-get-one-free deal: you gain skills and industry connections.