The phrase "once learnt" is grammatically correct and can be used in written English.
It is commonly used to indicate that something was learned in the past and is now a known fact or skill. Example: Once learnt, the skill of cooking became second nature to her.
Youngsters, off to university or to a new flat, see no point in paying for a fixed line when their lives are mobile and the habit, once learnt, will stay.
Once learnt, the rule is reversed and the length of time taken to adapt responding and learn the new rule is measured.
Once learnt properly, pelvic floor exercises can produce favourable results that can persist in many women for at least ten years.
This suggests that epidural catheter insertion may be a skill akin to riding a bike, that once learnt is rarely lost.
He suggests that his habit's roots might lie in something he once learnt in an acting class, about how a sharp noise can release tension.
Has America, where the best and brightest of the Gulf's investors and bankers once learnt the money game, now turned its back to Arab investment?
Specialists in anaesthesia will find it a quick and easy to read guide, to recapitulate the once-learnt but almost forgotten facts and principles depicted here as a concise compilation.
Describing pictures in books as "tremendously motivating" for children, he lamented a widespread assumption that, "once you've learnt to read, you don't need the pictures any more".
Once Danny had learnt that his love story was real – which was the key question to answer, for me – and re-evaluated his relationship with Scottie [Jim Broadbent] through this world, it was whether to close everything off or decide he'd found someone new and gone on this new adventure.
We assume in this case that the respondents will not use the useless route once they have learnt that it is highly unlikely to be the best travel option either when a risk-seeking attitude is applied or when more conservative behaviour is adopted.
Paradoxically, it's likely that we'll enjoy time with others even more once we have learnt to relax in our own company.
