This was of great concern because the number of polio cases shouldn't go up as the vaccine is being even more actively distributed through the country, so what happened?

这个现象让人担心,因为小儿麻痹症的发生数量,不应该在疫苗全国范围内普及后,反而有所上升,那么到底发生了什么

耶鲁公开课 - 生物医学工程探索课程节选

I'm concern about our safety "Maybe we should go some place else."

我觉得这儿不安全，“要不然换个地方吧。”

Let's 课堂 - SpeakingMax英语口语达人