once in a while

now and then or here and there; "he was arrogant and occasionally callous"; "open areas are only occasionally interrupted by clumps of trees"; "they visit New York on occasion"; "now and again she would take her favorite book from the shelf and read

झोंके कभी कभी भारी की संभावनाweather forecast

But there do arise once in a while some mutations that are either better or at any rate no worse than their originals.