Two studies of the social networking site recently appeared in the Archives of Pediatric and Adolescent Medicine.

VOA: special.2009.02.18

And this is my colleague, Marianne LaFrance, who is actually not smiling in that picture but she studies smiling and smiling in adults, smiling in children, smiling across cultures, and the different social uses of smiling.

另一位是我的同事，法国人玛丽安，她在照片上没有笑,但她研究微笑，成人的微笑，孩子的微笑，文明的微笑，微笑的不同社会功用。

耶鲁公开课 - 心理学导论课程节选

Top students in the ninth and tenth grades can attend single-sex classes for math,science,English and social studies.

VOA: special.2010.12.02

"There is absolutely no difference in the content of social studies, history,geography,math and science.

VOA: standard.2010.07.12