单项选择题

We often tend to associate smiling as the result of a positive event or mood. But research demonstrates that the act of smiling, in and 1 itself, can be the catalyst for joy. Wonderful things, ranging from an 2 mood to a better relationship, can be the result of the 3 act of smiling. Even better, it is a tool that is free, easy and always available.
Even when you aren"t feeling happy, smile can help 4 your mood. Darwin hypothesized, back in 1872, that making changes in our 5 expressions can influence our 6 experience, something he called facial feedback response theory. Psychological research has 7 Darwin"s assertion that expressions do not just result from moods, but actually influence them.
Smiling more may actually 8 your lifespan. Research indicates that smiling may improve heart health by 9 heart rate after stressful events. So, 10 smiling to your health regime of eating well, getting enough sleep and exercising may just add 11 years to your life.
People who smile more tend to be more 12 , joyful and emotionally stable which lends itself to healthier relationships, and thus have longer and more successful 13 . An interesting study published in 2009 found a correlation between smiles in photographs and divorce rates. The larger the smile, the 14 likely divorce was later in life. 15 , those with the smallest smiles or no smiles, were five times more likely to be divorced.
When Mother Teresa said "Every time you smile at someone, it is ... a 16 to that person, a beautiful thing", she was right. One study 17 by Hewlett Packard found that seeing another"s smile stimulated the heart and 18 more so than eating chocolate or receiving money. This was particularly true 19 viewing the smile of a child. Additionally, research has demonstrated smiling may actually be easily diffused. Research published in the Scandinavian Journal of Psychology examined mimicry, the tendency to mimic the emotional expressions of those around us, and found that it is actually hard to 20 when someone else is smiling.