背约

break an agreement
go back on one's word
fail to keep one's promise

备品, 背弃, 被侵害, 贝丘, 备取, 被褥, 焙烧, 背书, 倍数, 背水一战, 背诵, 倍塔, 备忘录, 背斜, 背心, 背信弃义, 背阴, 背影, 备用, 备用环, 倍增器, 备战, 背ぴ手, 备至, 备注, 被子, 辈子, 奔, 贲, 奔波, 奔驰, 奔放, 奔流, 奔忙, 奔命, 奔跑, 奔丧, 奔逃, 奔腾, 奔袭,