A..dwg B..sec C..drw D..prt
A..dwg B..sec C..drw D..iges
A.先下點(diǎn),后上點(diǎn),兩點(diǎn)豎直對齊 B.先上點(diǎn),后下點(diǎn),兩點(diǎn)豎直對齊 C.先左點(diǎn),后右點(diǎn),兩點(diǎn)水平對齊 D.先右點(diǎn),后左點(diǎn),兩點(diǎn)水平對齊