smoke是烟，there's no smoke without fire即“无火不生烟；无风不起浪”。

【例句】
He's denied having an affair with secretary but of course there's no smoke without fire.
他不承认他和他的秘书有染，但是无风不起浪啊。

Well, that's what they said, but there's no smoke without fire.
当然，那是他们说的，不过无风不起浪么。