精选优质文档-倾情为你奉上第一组：1. The vacuum cleaner is a valuable labor-saving _ action. A. device B. engine C. piece D. instrument 2. The flight was postponed because of technical problems and was finally cancelled last week when a _ was discovered. A. accident B. defect C. damage D. defeat 3. When she was crossing the road, she was knocked down by a motor-car and lay _ by the roadside. A. asleep B. thoughtless C. unconscious D. unaware 4. The novels he has written
