double layer flat cover双层平端盖
Double Disc Flat s双闸板平板闸阀
Double studio flat双人套间
double-flat U重降号
Double Disc Flat Gate双闸板平板闸阀
double-flat ໕重降号
double decked flat pallet双层托盘
double-flat E重降号
double-flat agitator双层桨叶
N(名词) an accidental that lowers the pitch of the following note two semitones 重降号; 表示要降两个半音的记号 (Usual symbol ♭♭)
N(名词) a note affected by this accidental 受重降号影响的音调
ADJ(形容词) denoting a note of a given letter name lowered in pitch by two semitones 音调降两个半音的