trough

n.波谷

troop-ship, trooper, trope, trophy, tropic, tropical, tropically, troposphere, Trot, troth, Trotskyism, Trotskyist, trotter, troubadour, trouble, trouble-maker, trouble-shooter, trouble-spot, troubled, troublesome, trounce, troupe, trouper, trouser, trouser-suit, trousers, trousseau, trout, trowel, troy weight, truancy, truant, truce, truck, truck farm, trucker, trucking, truckle, truckle-bed, truculence,