题目

阅读理解Astudy shows exposure (暴露) tomore light during the day and less light at night is important for people toget healthy sleep because it helps to keep the right body clock. The resultssuggest that in the office environment, being exposed to either sunlight orelectric lights that are rich in short wave blue light may be important for thehealth of workers.Tosee whether the office workers get enough light to regulate (调节) their sleep wake cycle,researchers found the participants (参与者) infive government office buildings across the United States. A total of 109people working 已知，若用含x的代数式表示y，则y（    ）