在棱长为1的正方体ABCD﹣A1B1C1D1中,四面体ACB1D1的体积为( )。
There is little we can do about it,_____? [ ]
A. is there
B. can't we
C. isn't there
D. can we
藏族主要分布在下列哪个省级行政区中( )
A.
B.
C.
D.