at sea

at sea (2)  {adj. phr.}
Не представляющий что делать; растерянный; потерянный.
The job was new to him, and for a few days he was at sea.
When his friends talked about chemistry, Don was at sea, because he did not study chemistry.
Ср.: AT A LOSS.
Категории: friends study {adj. phr.}