单选题 Crew chiefs supervised engines, switches and lights that told them how each item of equipment was functioning.
A. observed B. preserved C. monitored D. nurtured

【正确答案】 C

【答案解析】[解析] 本题中，supervised的意思是“监督，管理，指导”。四个选项中，monitored的意思是“监控”，如：a television wave form monitor(电视波形监视器)。observed的意思是“观察，遵守”；preserved的意思是“保护，保持”；nurtured的意思是“养育，教养”。只有C符合题意。