A:24°
B:25°
C:30°
D:36°
-- Wait a minute. Don’t cross the street _______ the traffic lights turn green.
大家都喜欢雪域高原西藏,它在下列何时获得解放( )
若2a+5b+4c=0,3a+b-7c=0,则a+b-c的值是( )