Option: DDDBCC

Fill in the blanks:

7, 60 degrees;

8, 165 degrees;

9、9;

10, complementary angle and complementary angle;

1 1, angle 4, angle 3, angle1;

12, the intersection point m is the vertical line of AB, and the vertical line segment is the shortest between two points.

This is all I can give you. Other steps are too complicated. I made it myself, and I can't guarantee that everything is right. Our teacher didn't answer correctly.