—________. If time permits, I may go to Shanghai with my friends.
A:Up to you
B:It depends
C:Forget it
D:Never mind
Don't _____________ too late, or you will feel tired in class.
图中的几何体,由两个正方体组合而成,大正方体的棱长为a,小正方体的棱长是b,则这个几何体的表面积等于( )
下面四句话,没有语病的一句是( )。