第三部分阅读理解 (共20小题；每小题2分，满分40分)
阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项, 并在答题卡将该项涂黑。
Tears are nature’s way of making us feel more comfortable. When our eyes is made uncomfortable by some small pieces of pollution, or when we are cutting onions, or when we are worn out and “red-eyes” from over work 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 human. We know that animals also experience emotion fear, pleasure, loneliness, but they do not shed (流) tears.
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 part, tears may actually constitute（构成）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 the emotional benefits, the shedding of tears has a specific biological function as well. Through tears, from our body we can get rid of certain chemicals which build up in response to stress and create a chemical imbalance in the body. Crying actually makes us feel better by correcting that imbalance and making us feel good again. And thus the emotional and the biological functions of tears merge (合并) into one and make us even more “human” than we would otherwise be.
56. According to the passage, human beings may have originated（起源）in __________.
A. the sea           B. the salt          C. chemicals          D. animals
57. Which of the following is NOT a function of tears?
A. Biological.        B. Emotional.       C. Political.          D. Chemical.
58. According to the article, which of the following is unique to humans?
A. The feeling of loneliness.              B. The state of feeling good.
C. The ability to shed tears.               D. The feeling of fear.
59. Which of the following is the main idea 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.