dud

adj defective; worthless 有缺点的; 不完善的; 无价值的; 无用的 * a dud cheque, ie one that is forged or not backed by cash 无用的支票（假支票或空头支票）.

dual-purpose, duality, dub, dubbin, dubiety, dubious, ducal, duchess, duchy, duck, duck-boards, duck-yard, ducking, duckling, ducks and drakes, duckweed, duct, ductile, ductility, ductless gland, dude, dudgeon, duds, due, due to, duel, duellist, duenna, duet, duff, duffer, duffle (also duffel), duffle bag, duffle-coat, dug, dug-out, duke, dukedom, dulcet, dulcimer,