in duty, on duty, off duty, duty free区别

B

in

duty有义务，有责任

as

in

duty

bound

有责任,

义不容辞

be

in

duty

bound

有义务(做某事)

be

in

duty

bound

to

do

sth.

有义务(做某事)

on

duty值班，当值

off

duty下班

Only

one

doctor

is

on

duty

today

-

the

other

doctor

is

off

duty.

今天只有一个医生值班，另一位下班了。

duty

free免税