一道英语选择题（顺便解释下意思）
He is often （ ）and can't sleep at night.
A.on vacation
B.in bed
C.at home
D.at school
So he has to do heavy work in the factory to look after the storehouse.He is often （ ）and can't sleep at night.So he feels tired in the daytime.He doesn't like his work.
A.on vacation
B.in bed
C.at home
D.at school