Some scientists speculate that Mars may have enjoyed an exte

Some scientists （主语）speculate（谓语） that Mars may have enjoyed an extended early Period during which rivers,lakes,and perhaps even oceans adorned its surface.（宾语从句）
下面是对宾语从句进行的分析
Mars （主语）may have enjoyed （谓语）an extended early Period （宾语）during which rivers,lakes,and perhaps even oceans adorned its surface（这是对定语从句加了一个定语从句）
一下是对定语从句的分析
during which rivers,lakes,and perhaps even oceans （主语）adorned（谓语） its surface（宾语）,这里的during which 在定语从句中充当时间状语
明白了吗