to back down

to back onto sth to badger sb for sth to badger sb with question to bail sb out to bale out to band together to bandy sth about to bandy words with sb to bang up to bank sth up to bargain on doing sth to barge in

double heical spur wheel double helical mixer double helical ribbon mixer double helical spur gear double helix double helix model double heterojunctionDHlasers double heterojunctionlasers double housing planer double hresholds