你知道太阳活动是有周期的。

You see the sun has cycles.

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热门的行业总是有周期的。

Hot businesses often go through cycles.

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以下事实证实了这点：与过去58年所有周期的任何可比阶段相比，供应商交货时间大幅延长。

This point is confirmed by the fact that supplier delivery times have lengthened proportionally more than at any comparable stage in every previous cycle of the past 58 years.

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You are allowed to use on the test the official version of the Periodic Table of the Elements which most of you should have by now.

在测试中你们可以使用,化学元素周期表的官方版本,你们应该大部分都有了吧。

麻省理工公开课 - 固态化学导论课程节选

So hopefully, it was a time issue in terms of looking at the periodic table, because let's have you tell me what are we looking for here?

希望刚才大家出问题的原因,是因为看周期表有时间限制，请大家告诉我,我们在这里找什么？

麻省理工公开课 - 化学原理课程节选

Relative to the whole market, It's well known that over periods of multiple decades the market has a tendency to go up.

是和整个市场相关的对吗，我们都知道经过几十年的时间周期,市场会有上涨的倾向。

麻省理工公开课 - 计算机科学及编程导论课程节选