mean business   (TTS發音)

be serious 嚴肅的；正經的

    When he said he was going to the library to study，he meant business. 他說他要去圖書館學習，他確實是認真說的。

    By sending their top people to meet our leaders at the summit conference，they really showed they meant business. 在這次最高級會議上，他們派出了他們的首領同我們的領袖見面，這表明他們是鄭重其事的。