Test analysis: According to congruent triangles's judgment method, Xiao Ming's thinking process is incorrect, so he should add the condition ∠B=∠C, so that he can draw a conclusion based on AAS certificate, or add the condition ∠A=∠D, so that he can draw a conclusion based on ASA certificate.

Solution: Xiaoming's thinking process is incorrect.

The condition of addition is: ∠B=∠C (or ∠A=∠D).

At △ A wave and △DCO.

.

Comments: congruent triangles's judgment and nature is the focus of junior high school mathematics, which runs through the whole junior high school mathematics study. It is a common knowledge point in the senior high school entrance examination, which is generally not difficult and needs to be mastered skillfully.