哭——这种人类特有的行为,是由痛苦、悲哀、恐惧或兴奋、愤怒、同情、焦虑等情感因素引起的。哭泣大多是不高兴的表示,但人在不哭时,眼睛也会分泌出少量的泪液,形成一层薄膜,用来滋润眼睛和为角膜供氧。人们哭的时间根据不同情况长短不等,一般一二分钟,短的几秒钟,长者数小时? Crying - This human-specific behavior is caused by emotional factors such as pain, sadness, fear or excitement, anger, compassion, anxiety, and so on. Mostly crying is unhappy, but when people are not crying, their eyes also secrete a small amount of tear and form a thin layer of film that nourishes the eyes and supplies oxygen to the cornea. People cry for a long time according to different conditions, usually a minute, a few seconds, the elderly for several hours?