Then when a stranger approaches or someone else approaches there they'll tend to give more of a greeting smile.

当陌生人或其他人接近时,他们是问候式微笑。

耶鲁公开课 - 心理学导论课程节选

When you speak in new language to somebody new on the streets in New York

当你用新的语言在纽约大街上同陌生人交谈时，

生存英语 - SpeakingMax英语口语达人