![Whydowelaugh?Foryearsscientistshaveaskedthemselvesthisq...]( "Whydowelaugh?Foryearsscientistshaveaskedthemselvesthisq...")
- 问题详情：Whydowelaugh?Foryearsscientistshaveaskedthemselvesthisquestion.Noanimalslaughandsmile–onlyhumanbeings,sodoeslaughinghelpustolivelonger?Theanswerseemstobethatsmilingandlaughinghelpustobecomecalmandlessworried,preventingillnesswhicharecausedby...
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