rivulet

n.小河, 小溪, 溪流

risky, risotto, risque, rissole, rite, ritual, ritualize, ritzy, rival, rivalry, rive, riven, river, river bed, river-bed, riverside, rivet, riveter, riveting, Riviera, riyal, rly, RM, RN, RNA, RNIB, RNLI, roach, road, road safety, road sense, road show, road tax, road test, road to, road-block, road-hog, road-house, road-mender, road-metal (also metal),