generate questions: In some languages, such as English, aspiration is allophonic. Stops are distinguished primarily by voicing, and voiceless stops are sometimes aspirated, while voiced stops are usually unaspirated.
Aspiration is what, in English and some other languages? {sep_token} How are stops distinguished? {sep_token} Voiceless stops are at times what? {sep_token} Voiced stops are most often what?