keep up with the pace of change
変化の速度について行く
keep up with the payments
期日に遅れないように支払う
keep watch (on ...)
(…の)見張りをする
keep within one's (proper) sphere
本領[本分]を守る
Keep your back straight at all times.
常に背筋を伸ばしていなさい
Keep your chin up!=Chin up!
((略式))がっかりするな,元気を出せ
Keep your elbows off the table.
テーブルにひじをつくな
Keep your grubby hands [paws] to yourself!
ちょっかいを出すな
Keep [Take] your mind off the job sometimes.
ときには仕事のことは忘れなさい
Keep your nose out of my business.
余計なお世話だ