VOA慢速英语:Filter Blue Light for Better Sleep

mobile - adj. able to move from one place to another

spectrum - n. the group of colors that a ray of light can be separated into including red, orange, yellow, green, blue, indigo, and violet : the colors that can be seen in a rainbow

actually  - adv. used to refer to what is true or real​

expose - v. to cause (someone) to experience something or to be influenced or affected by something

alert - adj. able to think clearly and to notice things

filter - n. a device that prevents some kinds of light, sound, electronic noises, etc., from passing through​

app - n. a computer program that performs a particular task (such as word processing)

screen - n.  the usually flat part of a television or computer monitor that shows the images or text : the part of a television or computer that you look at when you are using it

intensity - n. the usually flat part of a television or computer monitor that shows the images or text : the part of a television or computer that you look at when you are using it

operating system - n. the main program in a computer that controls the way the computer works and makes it possible for other programs to function

schedule - v. to plan (something) at a certain time

specific - adj. special or particular​

swipe - v. to make a sweeping stroke

introduce - v. to make (something) available for the first time​