网址：http://m.1010jiajiao.com/timu_id_788108[举报]
It is impolite to leave the meeting finishes.
A．after
B．before
C．until
D．while
A．after B．before C．until D．while
________ we were singing happily, he came in．
A．While
B．After
C．Until
D．Before
I met your brother ______ I was walking in the street.
A．before
B．until
C．after
______ Kathy was watching TV, her mother asked her to go shopping.
A．Before B．Until C．While D．After