Not that I knew!

[Tom]

Hi

In a comprehension passage that I was reading last night a boy tells his sad story of one day when he was cycling and got hit by a car.He fainted. (The next paragraph starts with the given line)

Not that I knew.

What does he want to say? That he did not know what happened later or that he fainted? Is it an idiomatic expression?

Tom

[Mister Micawber]

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You have not given us enough context on this one, Tom. Give us the text before and after.
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_________________
Native English teacher at Mister Micawber's

[Tom]

OK, Mister Micawber

Here it is! :D

" As I rode through an intersection, a car sped recklessly through a give-way sign. It smashed my bike from beneath me. I flew over the roof, landing on top, bouncing off and falling unconscious on the road behind. Not that I knew. I remember nothing. A crack in my helmet suggests why. I am only alive because of my helmet."

Q1: What is a give-way sign? (We do not have it in Pakistan)

Q2: Does the roof mean the roof of the car?

Q3: Not that I knew: Could you please explain it a bit? Is it a complete sentence? What did he not know?

Q4: Landing on top: Does it mean top of the car?

Q5: Road behind: Behind what? Does he mean behind the car?

[Mister Micawber]

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Ah! I see now, thanks.

Q1: What is a give-way sign? (We do not have it in Pakistan) -- A 'Yield' sign: if there is cross-traffic, you must wait until it passes the intersection.

Q2: Does the roof mean the roof of the car? -- Yes

Q3: Not that I knew: Could you please explain it a bit? Is it a complete sentence? What did he not know? -- Not a complete sentence, but a complete utterance. He has just given a description of the accident, but then cautions us that he did not know what happened, actually-- his memory is a blank.

Q4: Landing on top: Does it mean top of the car? -- Yes

Q5: Road behind: Behind what? Does he mean behind the car? -- Yes.
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_________________
Native English teacher at Mister Micawber's