Collocations for concentrate - verb

fiercely, hard, intently
She was sitting at her desk concentrating hard.

fully, properly | mainly, predominantly, primarily | particularly | entirely, exclusively, purely, solely

be unable to, can''t, couldn''t
I tried to work but I found I couldn''t concentrate.

be difficult to, be hard to, be impossible to | tend to
UK banks tend to concentrate on short-term lending.

try to

on/upon
He concentrated mainly on the flying and spoke very little.