If the two extracted ones are ① ②, we can get △ Abe△ DCE, be = ec.
If ① ③, AE=DE, AB=CD, △ Abe △ DCE cannot be obtained, ∴ This situation is not true;
If ① ④, we can get △ Abe△ DCE, be = ec.
If ② ③, you can also get △ Abe△ DCE, be = ec.
If ② ④, the three angles are equal, but the side lengths are not necessarily equal, it is not true.
If ③ ④, be = EC can also be obtained.
So, the answer is: ① ③; ②④.
(2) Using ① and ② as conditions, it can be judged that △BCE is an isosceles triangle.
∫AB = DC∠ABE =∠DCE，
∫∠AEB =∠DEC again.
∴△ABE≌△DCE(AAS)，
∴BE=EC, that is, △BCE is an isosceles triangle.