The first is the completeness of the answer. When you answer a question, you should not only complete the answer, but also give detailed information to support your argument. For example, just answer "I like going to the park when I am relaxed." Because the first park has good air, the second one has green trees and flowers to make me feel good, and the third one can take pictures in the park. "This is incomplete and lacks more detailed information to support this argument. Why is the air in the park good? How do green trees and flowers make you feel happy? Adding more details can enrich the answer.

The second is the authenticity of the answer. The tunnel here is not only pronunciation and intonation, but also vocabulary and phrases, which should conform to the habits of native English speakers. For example, "changing classes" is more in line with American habits than "changing A into B". Use "everything is ready" to express that everything is in order. Using more expressions that conform to American habits will make your oral English more "authentic" and prove to the examiner that you can fully adapt to American study. Choosing different words to express the same meaning is a "signal" for examiners: it shows that candidates have a certain language foundation.

Practice oral English often, there is no other shortcut.