隋朝开凿的大运河北段是（）
A.通济渠
B.永济渠
C.邗沟
D.江南河
参考答案：B
If you smoke, please go outside.
A．can
B．should
C．must
D．may
A．Depressed and disappointed.
B．Tired and sick.
C．Sad and lonely.
D．Confused and frustrated.
