Could you speak English when you were six или Can you speak English when you were six?

Question

Could you speak English when you were six или Can you speak English when you were six?

Answer 1

Could you speak English when you were six?


could - II форма от can, значит, нам нужен именно этот глагол)

Answer 2

Could you speak English when you were six?
Can — это "можешь" (можете) или "умеешь" (умеете), то есть настоящее время, а could — "мог" (могла) или "умел" (умела), то есть прошедшее время.

Поэтому первый вариант.