今日の表現

self-starter
自発的な人

someone who is able to work
sucessfully on their own without 
needing other people's help or
a lot of instructions
(Longman)

look over one's shoulder
びくびくする

to feel worried that somethig
unpleasant is going to happen
to you
(Longman)

drop the ball
失敗する

to make a mistake when dealing with
something because you stop thinking
carefully or paying attention
(Longman)

同意表現
take your eye off the ball