from time to time
  有時,時常,偶爾
  from time to time
       adv : 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" [syn: occasionally, on
             occasion, once in a while, now and then, now and
             again, at times]