(1) It is known that ∠ 1 is 30, ∠2 is 30, and the sum of them is 60, which is still an acute angle.

(2) a is-1, B is-1, ab is 1, which is greater than 0, but both A and B are not positive numbers.

(3) Only when a group of parallel lines intersect a straight line, the congruence angles obtained are equal.