两个都不对,首先of后面不可用that从句,其次,根据语境,period后面的从句引导词用when不是that。
首先,of 是介词,后面接的是介词短语,可以做定语。你给的句子错在,of 后面直接跟的句子,不是介词短语!
而定语从句,是完整的句子。
其次,很遗憾!你所给的两个句子都不对啊!可以修改为——
I think we are living in a period of
everybody becoming famous.
I think we are living in a period when/
in which everybody can become
famous.
动词不定式在这里做后置定语,修饰前面的reason,翻译成迟到的理由
迟到是be late