The phrase "be appreciative" is often used to express gratitude or thankfulness. There are many synonyms that can be used to convey the same meaning, including "be grateful", "show gratitude", "express thanks", "give thanks", "acknowledge", "be obliged", "be in debt", "be thankful", "show appreciation", "recognize", and "value". These synonyms can be used interchangeably in various contexts and situations to express gratitude towards someone or something. In everyday conversations, it is important to use polite and respectful language to show appreciation and gratitude towards others.