The two countries have not had formal relations since Iran's 1979 Islamic revolution and interaction between the two countries' diplomats has been infrequent.

VOA: standard.2009.06.24

It's not infrequent that i'll get one or even two people raising their hand that they took Economics 252 from me.

有的时候会有一两个人,举起手说,他们上过我的经济学252号课

耶鲁公开课 - 金融市场课程节选