Sunlight is the main source of blue light, and 38 outdoors
during daylight is where most of us get most of our exposure 39
it. But there are also many man-made, indoor sources of blue
light, 40 fluorescent and LED lighting and flat-screen
televisions. Most notably, the display screens of computers,
electronic notebooks, smartphones and other digital devices 41
significant amounts of blue light. The amount of time people
spend using these devices and the proximity of these screens to
the user's face have many health care professionals 42 possible
long-term effects of blue light on eye health.
【題組】38. (A) is (B) are (C) be (D) being