The dollar has plummeted more in Bush's term than during any comparable period of US history.

布什执政期间，美元继续暴跌,这在美国历史上绝无仅有。

斯坦福公开课 - 经济学课程节选

That is before there is any written evidence from the period in which you are interested.

那是一个你所感兴趣,而无任何书面记录的时代

耶鲁公开课 - 古希腊历史简介课程节选

The return, of course, in any given time period is the percentage increase in the portfolio; or, it could be a negative number, it could be a decrease.

当然了，收益率是一定时间内,投资组合的增长率;,也可能是一个负数，表示负增长。

耶鲁公开课 - 金融市场课程节选