The clothing store ____________ a sale. The clothes there are very cheap(便宜的).
A:has
B:had
C:is having
D:was having
如图,AB是半圆O的直径,AC为弦,OD⊥AC于D,过点O作OE∥AC交半圆O于点E,过点E作EF⊥AB于F,若AC=4,则OF的长为( )
2×9=____
4×5=____
3×4=____
2×5=____
6×3=____