When you're talking about festivals and about special periods of time, you can use " at" .

当你在谈论节日和特殊的时间段时，你可以用" at" 。

So please, try to remember the most special period for our development is the first five years.

所以，请牢记，我们成长发展阶段中的黄金时期是出生后的最初五年。

These hospitals have also been ordered to dispatch medical personnel to county hospitals to assist during special periods, including the Spring Festival holiday.

三级医院要求在包括春节假期在内的特殊时期向县级医院派遣医务人员提供援助。