ne sachant pas quoi dire
Not knowing what to say, I remained silent.
Ne sachant que dire, je suis resté silencieux.
Not knowing what to say, he remained silent.
Ne sachant que dire, il resta silencieux.
Not knowing what to say, she remained silent.
Ne sachant que dire, elle resta silencieuse.
Not knowing what to say, I kept silent.
Ne sachant que dire, je suis resté silencieux.