主语是“物”， be ready 后的不定式跟主语存在动宾关系时，用被动式或主动式均可以。主动时，可以看作在不定式之前省略了由 for 引出的逻辑主语。例如：

The apples are ripe and ready (for us) to eat. 苹果完全熟了，随时可以享用。

You need to boil the dumplings for 10 minutes, and then they will be ready (for you) to eat.  你得把饺子煮上十分钟才能吃。

In a few days time the sprouts will be ready (for them) to eat. 再过几天球芽甘蓝就可以吃了。

《柯林斯高阶英汉双解学习词典》

Soon the bananas would be ready (for the children) to eat. 很快香蕉就能吃了。

以下是用被动式的句子：

I have wrapped up the parcels and they're ready to be posted. 我把包裹都包好了，可以寄出去了。

The potatoes are ready to be dug up. 快要收获土豆了。

The steel is then ready to be cast into different shape and size. 这时的钢水可以被浇铸成各种大小不同的形状。