It is a mere coincidence.

这只是巧合而已。

It is impossible that it should be a mere coincidence.

这不可能仅仅是巧合。

Lots of things happen by mere coincidence in this world.

世界上往往有许多巧事，是你没有想到的；

(I swear it's a mere coincidence that I wrote about the commercialization of female pleasure just yesterday.) Moynihan writes

我发誓这和我昨天刚刚写的女性享乐的商业推广是单纯的巧合。

(I swear it's a mere coincidence that I wrote about the commercialization of female pleasure just yesterday. ) Moynihan writes

我发誓这和我昨天刚刚写的女性享乐的商业推广是单纯的巧合。