Shedding tears(流泪) is a natural way of making us feel more comfortable．When our eyes are made uncomfortable by some small pieces of pollution, or when we are cutting onions, or when we are exhausted(精疲力竭; 疲劳) and have “red-eyes” from overwork and late hours, tears form in our eyes to clean and refresh them．
Tears are also a sign of strong emotion．We cry when we are sad and we cry when we are happy．
And tears seem to be uniquely (惟独) human．We know that animals also experience emotion ——fear, pleasure, loneliness——but they do not shed (流) tears．From this, we can conclude that tears are closely related to the emotional and biological make-up(结构；组成) of the human species．
Biologically speaking, tears are actually drops of saline fluid, which is a little bit salty, produced by a gland (腺) in the body．Because salt is an important component, tears may actually constitute the most conclusive evidence that the human animal is the end product of a long evolutionary process that began in the sea．
And it is clear that, in addition to (除了) the emotional benefits (好处), the shedding of tears has a specific biological function as well．Through tears, we can eliminate from our body certain chemicals which build up in response to stress and create a chemical imbalance(不平衡) in the body．Crying actually makes us feel better by correcting that imbalance and making us feel good again．And thus the emotional and biological functions of tears merge (合并) into one and make us even more “human” than we would otherwise be．
60、According to the passage, human beings may have originated (起源于) in_______．
A. the sea B. the salt C. chemicals D. animals
61、Which of the following is NOT a function of tears?
A. Biological B. Emotional C. Political D. Chemical
62、The underlined word “eliminate” probably mean_______．
A. add B. produce C. replace D. remove
63、Which of the following is the best title of the passage?
A. Tears are a sign of strong emotion．
B. Tears are always making us feel more comfortable．
C. Tears are uniquely human．
D. Tears have certain biological function．