He smiled knowingly.

他会意地笑了。

《柯林斯英汉双解大词典》

And he smiled knowingly.

他会意地微笑着。

youdao

He smiled knowingly, and went back to his book.

他心照不宣地笑笑，然后又返回到他的书上。

youdao

While he spoke to us, we simply nodded knowingly and smiled.

他说的时候，我们只是不停地笑着点头。

youdao

While he spoke to us, we simply nodded knowingly and smiled.

他说的时候，我们只是不停地笑着点头。

youdao