What are some important details from Mayella Ewell's testimony under Mr. Finch's questioning in To Kill a Mockingbird?

Uneducated and coerced into lying by her disreputable father, Mayella gives testimony that is so unsustainable that Atticus easily challenges its credibility.

While Mayella is on the witness stand, Atticus begins by asking her if the day of the alleged rape was the first time Tom had ever been inside the fence of her yard, and she replies "yes." Her answer raises some doubt, of course, because within the setting of the Jim Crow South, it would have been outrageously bold for a black man to have dared to commit rape without having had some prior close contact with a white woman. 

When Atticus asks Mayella what occurred, she hesitates. So, he asks her specifically if she recalls Tom's having beaten her about the face. She replies,

• "No, I don't recollect if he hit me. I mean yes I do, he hit me."

Atticus asks her to verify her last statement:

• "Huh? Yes, he hit--I just don't remember, I just don't remember...it all happened so quick."

Then, she oddly accuses Atticus of mocking her. Subsequently, Atticus has Tom stand up as he asks Mayella if Tom is the man who raped her. Mayella responds with confidence:

• It most certainly is." (This answer is in contrast to her previous answer that is uncertain.)

Next, Atticus asks Mayella "How?" and she rages,

• "I don't know how he done it, but he done it--I said it all happened so fast I--" (Again Mayella acts as though she does not remember. Her vagueness is questionable.)

Atticus, then, reviews for Mayella what she has said so far, and asks, "He choked you then?" and she replies, "Yes." Further, Atticus asks, "He blackened your left eye with his right fist?"

• "I ducked and it--it glanced that's what it did...." (Significantly, Mayella does not deny that Tom used his right arm.)

Atticus continues his questioning, asking if Tom choked her, hit her, and raped her. Now, it seems that Mayella is sure: 

• "It most certainly is."

Atticus asked her if she fought Tom and screamed, and Mayells says that she did. When Atticus asks her why none of her seven brothers and sisters responded, there is no answer. "Where were they?" Atticus asks. Again, there is no answer from Mayella.

Continuing this questioning, Atticus asks, "Why didn't your screams make them coming running? The dump's closer than the woods, isn't it?" Still there is no answer from Mayella.
He gets the same "no answer" when asking Mayella if she did not scream until she saw her father. Then, he asks,

"Did you scream first at your father instead of at Tom Robinson? Was that it?"
No answer.

"Why didn't you tell the truth, child, didn't Bob Ewell beat you up?"

Still Mayella does not answer. After Atticus turns his back, Mayella blurts out in rage that she "got somethin' to say" and she emotionally attacks the "fancy gentlemen" in the jury and Atticus with his "fancy airs." Here Mayella tries to reduce the questioning of Atticus to a simple belittlement of her just because she is poor. As she leaves the stand, Mayella glares with hatred at Atticus.