I sometimes see such a phrase:
It's kind of difficult.
There is not an article before "kind" here.
So, I am not sure if I can say like this or not.
They are kind of fruit.
I usually say like this:
They are a kind of fruit.
I guess "a kind" in the third sentence and "kind" in the first sentence have different meanings, but I would like to know whether it is actually possible to say, "They are kind of fruit" or not.