These food are good to eat. 这里to eat是被动语态?充当什么语?

此处是adj./过去分词＋to do句型，to do跟在形容词之后做状语成分。(1).当前面形容词是表示情绪的词时，to do表示产生这种情绪的原因。
e.g. I am glad to hear the news.
I was surprised to see him there.
(2).前面是其他形容词时，to do用以说明谓语所表示的情况。
e.g. He is difficult to get along with.他很难－（难什么）说明：难相处
These food are good to eat. 这些食物好－好在哪里，说明谓语的情况：这些食物好吃。

这里是用不定式主动形式表示被动意义。
如 The stone is hard to break.
It is easy to understand.
The meat is not fit to eat.
The book is difficult to read.

此句型属于省略不定式逻辑主语的句子，因为他们的逻辑主语没必要说出，不定式做定语。
There are so much work (for us) to do.
He's a little boy (for me)to take care.
This is a difficult question (for me) to answer.
The question is difficult (for me) to answer.

不是被动,形容词后接不动式,应该看作一种固定搭配,但有的语法学家将这种不动式称作宾语.其与句子主语是主谓或动宾关系.在这里,these food 和to eat是动宾关系.
参考薄冰高级语法.

是补语啦。
These food are good。 完全可以成为一个简单句。

这个跟 These food taste good 是不一样的。

这里是用不定式主动形式表示被动意义。