Every dog has its day

也许就是今天

别把自己幻想成丰田汽车
每一条街头巷尾都该有你

别把自己幻想成野生长白山人参
深藏不露却人人寻觅

每个人有自己的一亩三分田
每只狗有它自己的那一天

也许就是今天

-- 茶茶

Every dog has its day
英文谚语，直译是每一只狗都有它的那一天，实际意思是人人都有走运的时候。

has its day
has his day
has her day
have your day
have my day

上面这些词组都是说某某（它/他/她/你/我）走运（当红，兴盛）的意思。has 或是 have 是属于 【现在式】，所以这走运就是目前的事，不是过去的事。

那么，有趣的事来了：
如果把 has 或是 have 改成【完成式】has had 或 have had， 那会怎样呢？且看看：

HAS its day ==> HAS HAD its day
有它的日子 ==> 已经有过了它的日子

如果前者代表走运，那么后者就代表走过了运。换句话说，不再走运了。

Writing letters has had its day.
写信（这回事）已经过时了。

Arnold Schwarzenegger has had his day.
阿诺施瓦辛格已经过时了。