SELECT qe.id, qe.content, a.id, a.content, a.dt, acr.checked, acr.score
FROM `questions_and_exercises` qe,
`questions from-to` qft
LEFT JOIN `questions-answers` qa ON (qa.qid=q.id AND qa.uid=?)
LEFT JOIN answers a ON (a.id=qa.aid)
AND qft.to_lid=?
AND qft.uid=?
