When people reunite with their loved ones, it's usually all extremely happy moment. But what is their most common response to seeing them again? It may seem strange，but most of the time they break down in tears.

    Now a group of psychologists from Yale University say they have found the reason why, and that crying tears of joy may well be the body's way of keeping emotional balance. “They seem to take place when people are overtaken by strong positive emotions, and people who do this seem to recover better from those strong emotions,” Oriana Aragon, the lead researcher said.

    Aragon and her fellow psychologists looked at hundreds of participants' emotional responses to different things, including happy reunions and cute babies. Many participants said they would react in a negative or aggressive way to the positive things —— to cry at happy moments and want to pinch(捏)a cute baby's face or even tell them “I want to eat you up!” But then researchers found that these people were able to calm down from strong emotions more quickly.

    There are many other examples of times when people respond to a positive experience with a negative emotional reaction. At an exciting concert, fans scream at their idols(偶像). People who have just had a big lottery win are often in floods of tears. “These findings advance our understanding of how people express and control their emotions, which is importantly related to mental and physical health, the quality of relationships with others, and even how well people work together.” said Aragon．

    It was a very cold evening. The old man's beard was almost icy. He was waiting for a 1 across the river. The wait seemed 2. The old man sat on the ground waiting for quite a long time.

    3, he saw several horsemen coming. He watched them silently and let the first one pass by without even asking. Another passed by, and then another, till the last rider came near the old man. The old man caught the rider's 4 and said, “Sir, would you 5 giving me a ride to the other side?”

    6 his horse, the rider replied, “Of course not.” But it was so cold that the old man's body was almost 7. He could not get 8the ground. The horseman helped the old man onto his horse. He took the old man not just across the river, 9to the old man's home.

    As they 10 the old man's house, the horseman asked, “Sir, you let several other riders pass by without even asking. Then I 11 and you asked me for a ride at once. Why? 12 I had said 'no' and left you there?”

    The old man looked the rider straight in the eye, and said, “I looked 13 the eyes of the other riders. I quickly saw that they didn't 14. It would be 15 even asking them for a ride. But in your eye I saw 16. I knew that you would help me.”

    The words 17 the rider deeply. “Thank you for what you've said,” he told the old man. “I hope I will never leave others 18 simply because I'm busy, and every American citizen does 19 in my heart.”

    With that, Thomas Jefferson, the third president of the US, turned his horse around and made his 20back to the White House.

— Sorry, I _________ it. I guess I put it on the top shelf with my things.