I'll try but I can't promise.我争取去，但不能保证

今天的几个句子是有关约定的：1.You can't tell anyone. 你不能告诉任何人。2.Remember to bring the report. 记住带上你的报告。3.A promise is a promise! 说到就得做到。4.You can't go back on your promise now! 你现在不能食言。