Example : As distant and bemused as a professor listening to the prattling of his freshman class.
Lost in thought.
A preoccupied frown.

Synonyms : lost, preoccupied

Example : Obviously bemused by his questions.
Bewildered and confused.
A cloudy and confounded philosopher.
Just a mixed-up kid.
She felt lost on the first day of school.

Synonyms : at sea, baffled, befuddled, bewildered, confounded, confused, lost, mazed, mixed-up