(2) Two straight lines are cut by the third line. If the internal dislocation angles are equal, two straight lines are parallel.

(3) Two straight lines are cut by the third line. If they are complementary to each other, the two straight lines are parallel.

(1) If two straight lines are parallel, they are equal to the complementary angle;

② If two straight lines are parallel, the internal dislocation angles are equal;

(3) If two straight lines are parallel, the internal angles on the same side are complementary.

Hope to adopt.