Biliyor: mean" know" why you translate it as "speak" ??
Because in English, you normally say "I speak X language" instead of saying "I know X language." We accept both answers though :)
Konusmak and soylemek are never used?
بله میتوانید sen رو هم حذف کنید.
Somewhere(outside Duolingo) i saw it this way: Ingilizce konuşabiliyor musun. ? I think this is also good translate because it adds additional meaning to a sentence?