海阔天空hǎi kuò tiān kōng形容大自然的广阔,也比喻想像或说话毫无拘束,漫无边际{as boundless as the sea and the sky; (fig.) endlessly vast; (of speech or imagination) unrestrained and far-ranging; discursive}: 两人都很健谈,~,聊起来没个完。{They were both talkative and had a rambling chat about everything under the sun.}