重棒眼，双棒眼，超棒眼[黑腹果蝇唾液腺染色体的X染色体上16A区段重复三次而出现的特殊表型]

the Double Ninth Festival;Chongyang Festival

Double-Seventh Day；The Double Seventh Festival

double focusing

double pane

double-ended tubular lamp

double dissociation

double-sideband suppressed-carrier modulator【通信】

double decomposition reaction