A:Have...met; has drive
B:Had...met; was drive
C:Did...meet; had been drive
D:Have...met; had drive
现有四种说法:①-a表示负数; ②若|x|=-x,则x<0; ③绝对值最小的有理数是0;④3×102x2y是5次单项式;其中正确的是( )
一个几何体的三视图如图,则该几何体的表面积为