填空题

Why do we laugh For years scientists have asked themselves this question. No other animals lau
gh and smile--only human beings, so does laughter help us to (36) in any way The answer seems to be that smiling and laughter help us to relax, reducing (37) and preventing illnesses which are caused by stress. Laughter really is the best (38) !
But if you’re unhappy, it can’t do you any good to smile, can it Not true. Apparently the (39) effects of smiling are just the same (40) you feel like smiling or not. Scientists in California asked a group of (41) to act five different feelings: happiness, sadness, (42) , surprise and fear--just using their faces.
Changes in their heart rate, blood pressure and temperature were (43) down. Most of the feelings they acted didn’t cause changes, but when they smiled their heart rate and their blood pressure went down. (44) . A sense of humor also helps to keep things in perspective. (45) .So if you find yourself in a stressful situation, try to let yourself [giggle](咯咯地笑). A psychologist writes: " (46) .If you start to laugh, in time you will actually become happier.\