abreast of
adept in
at home in
au courant
briefed
educated
enlightened
expert at
good at
handy at
informed
instructed
master of
posted
primed
proficient in
schooled
skilled in
strong in
taught
trained
up on
up-to-date
versed
versed in
well up on
well-educated
well-grounded
well-informed
well-posted
well-read
widely read