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Should it be:

How did you know I spoke English. Or

How did you know I speak English. Or

How do you know I speak English.

This is when talking to someone in the elevator using the present tense. The person automatically started talking to me in English.
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PreciousJones1. How did you know I spoke English?
2. How did you know I speak English?
3. How do you know I speak English?
This is when talking to someone in the elevator using the present tense. The person automatically started talking to me in English.
Those are all questions, so they should all end with a question mark '?'. I've added them in the quote.

Number 1 is idiomatic. The best I can explain it, and I may be wrong, is that you're imagining a time in the past when this person found out that you could speak English. At that time, he knew that you SPOKE English, and you are asking him HOW he found out. It's very difficult to explain but it's the idiomatic, normal form, I believe.

Number 2 also sounds OK to me.
Number 3 is unnatural. If someone starts speaking English to you in the elevator, he already knows that you speak English, so he DID know BEFORE he started speaking to you.
"How DO you know ..." is used in a different way. It is questioning the accuracy or validity of something someone has said. For example, "It's going to rain today". "How do you know that?" "I heard the weather forecast".

HTH KrisBlueNZ

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Actually, number 2 should be "How did you know I COULD SPEAK English?" which means the same as "How did you know I WAS ABLE TO speak English?".
Actually all three happened in the elevator during the present, so which one is the best answer?
I'd choose "How DID you know I COULD SPEAK English?" (suggestion number 2 with COULD added into it). Otherwise number 1 is okay - "How DID you know I SPOKE English".
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