A:were not grading
B:have already been graded
C:were still being graded
D:have not grading
With winter ____(到来), leaves of trees turn yellow and begin to fall.
下列四图中,代表傣族的是( )
如图,正六边形ABCDEF内接于⊙O,⊙O的半径为1,则弧AB的长为 ____.