Most people are good at recognizing the universal facial expressions of our emotions — anger, joy, sadness, etc., which present a lot of emotional information. In fact, there are less obvious facial expressions called micro-expressions (MEs). general, human beings often show them and communicate (they) private thoughts to others unconsciously. What's more, people cannot hide them, including the experienced ones.
All the (finding) lead to many possibilities of MEs' wide use in different fields, people can use MEs to understand other people's true feelings, thoughts, or beliefs. Police can use MEs to detect unnatural behavior. Teachers can recognize unease in students and give a more detailed (explain). Businessmen can use expressions of happiness to determine when they have given a suitable price.
However, MEs are difficult (read), because they are unconscious, and occur sometimes as fast as one-tenth of a second or even one-fifteenth of a second. At present, even highly (train) people are not always able to notice them. Some people do see something that (change) on the face, but they don't know (exact) what it is. Since the human recognition accuracy (准确)is so low, possible method for spotting MEs would be very precious.
