Another key event in the making of modernism is the great migration of African-Americans from the rural south to the urban north.

现代创作的另一个重要事件,是非裔美籍从南部乡下,往城市化的北部的大移民。

耶鲁公开课 - 现代诗歌课程节选

In another example, you can use a "when" question in order to ask about the timing of a specific event.

在下面这个例子中，你可以用When 问句来询问一个具体活动的时间。

When 课堂 - SpeakingMax英语口语达人