Passengers are required to keep their seat belts securely ______________ during takeoffs and landings.Đoạn văn16/55Mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions. Passengers are required to keep their seat belts securely ______________ during takeoffs and landings. attachedclosedfastenedstrappedGiải thíchChọn C