一、句子结构分析
让步状语：Although in his seventies at the time of the interview （是 although Picasso was in his seventies 的省略）虽然在采访的时候（毕加索）已经是70多岁
主语：Picasso
系动词：proved 显出来的是（证明是）
表语：alert and insightful,思维敏捷和富有洞擦力的
独立主格结构作伴随状语：his faculties intact despite the inevitable toll of the years.尽管寿命亡鈡要不可避免响起,他的才能是完整无损的（“独立主格 + 形容词短语”）其中——
【逻辑主语】his faculties
【表示特征的述语】intact despite the inevitable toll of the year（形容词可以用在独立主格结构中叙述该结构中逻辑主语的特征或状态）
二、此处的独立主格结构也可以改写如下：
(at that time) his faculties (was) intact despite the inevitable toll of the years.
再把 was 改为分词 being：at that time his faculties (being) intact despite the inevitable toll of the years
不过,很少用“being + 形容词”构成独立主格结构,being 一般不出现.
参考译文：虽然在采访毕加索时他已经70多岁,但是他却显得思维敏捷和富有洞擦力,尽管此时亡鈡即将敲响,他的才能还是依然如故.