Ron gave her a knowing smile.

罗恩向她报以一个会意的微笑。

《柯林斯英汉双解大词典》

When asked who sent them just give a knowing smile.

当人家问你是谁送的时，只要回以一个会意的微笑。

youdao

"You'll find out on Valentine's Day." he said with a knowing smile.

“到情人节那天你就会知道了。”他笑着说。

youdao

When asked if a woman could successfully juggle a career and a family, she offered a knowing smile.

FORBES: This Nobel Laureate (and Mother of Six) Says Women Can Have It All

This time, her smile was slow and deliberate a knowing, almost ironic smile, the kind of smile exchanged between conspirators.

NEWYORKER: Sweetheart Sorrow

For all their bright saris and painted faces, these paragons remain appropriately stand-offish, knowing full well that if they adopt a more genial demeanor or even, God forbid, smile, there might be unspeakable scenes of male forwardness.

CNN: From Our Correspondent: On a Magical Hill