Translation of "Relation" in Chinese

In relation to this, I am to blame.

關於這件事，我必須負上責任。

She really does not have a relation to this business.

她真的和这件事无关。

I had a lot to say in relation to that affair.

關於那件事我有很多話要說。

His claim is that there is a close relation between birth order and personality.

他主張的是出生的先後次序和個性有很密切的關係。

I can describe China, especially in relation to big cities like Beijing, in one sentence - China is a country whose pace of life is both fast and leisurely.

我能用一句话描述中国，尤其是关于北京那样的大城市：中国是一个有悠闲生活并有快速生活的国家。