He told me that he has been 23.
He told me of his age of 23.（也可以用简单句）
He told me that he is 23.
谓语肯定用过去式,如果这件事发生在不久前,也就是说他现在还是23岁,那从句为客观事实,时态不变,现在范畴时态.
如果他现在已经不是23了,那就是过去客观事实,时态为过去式.
He told me that he was 23.
He told me that he has been 23.
He told me of his age of 23.（也可以用简单句）
He told me that he is 23.
谓语肯定用过去式,如果这件事发生在不久前,也就是说他现在还是23岁,那从句为客观事实,时态不变,现在范畴时态.
如果他现在已经不是23了,那就是过去客观事实,时态为过去式.
He told me that he was 23.