宣告 (xuāngào) is a formal, often dramatic verb meaning 'to proclaim, to declare' — it's used for major public announcements like declaring war, a state of emergency, or bankruptcy. It's more solemn and weighty than 宣布 (xuānbù), which is the everyday word for 'to announce' (e.g., a meeting or decision). 声明 (shēngmíng) is a verb/noun for 'to state, to declare' in an official or public statement, often to clarify a position.