Which of the following descriptions about the giving dimension for mechanical drawing are correct?

A、The dimension lines of linear dimensions must be parallel to the segments which are
dimensioned.
B、The dimension figures of horizontal dimensions should be drawn upward above the dimension lines; those of vertical dimensions should be drawn leftward on the left of the dimension lines; and those of oblique dimensions should be drawn at upward direction and placed over the dimension lines.
C、The arrows of continuous dimensions should be drawn aligned.
D、For parallel dimensions, the larger ones should be placed outside of the smaller ones, and the distance between two parallel dimensions should be 5～10mm.