A fire-fighter……….severely while he……….to put out a fire. A. was being injured - would help B. has been injured - helped C. had been injured - has helped D. was injured - was helping18/30A fire-fighter……….severely while he……….to put out a fire.was being injured - would helphas been injured - helpedhad been injured - has helpedwas injured - was helpingGiải thíchChọn D