on certain occasions or in certain cases but not always; "sometimes she wished she were back in England"; "sometimes her photography is breathtaking"; "sometimes they come for a month; at other times for six months"
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 to us"; "as we drove along, the beautiful scenery now and then attracted his attention"