ravine

n deep narrow steep-sided valley between mountains 既深且狭、 坡度很大的山谷.

rattan, ratter, rattle, rattlesnake, rattling, ratty, raucous, raucously, raucousness, raunchily, raunchiness, raunchy, ravage, rave, ravel, raven, ravening, ravenous, ravenously, raver, raving, ravings, ravioli, ravish, ravishing, ravishingly, raw, raw material, raw-boned, rawhide, rawness, ray, ray (also re), rayon, raze, raze (also rase), razor, razor-back, razor-blade, razor-edge,