I remember having learning that に can be used for a simple emphasis of the word before it, like so:
私はケーキを食べた - I ate cake
私にはケーキを食べた - I ate cake (the others may or may not have, but I did)
But then I stumbled upon something about the に for emphasis not being able to be used in with verbs that normally can't take it? Does this mean the following sentences are incorrect, since 知る can't be used with に?
Or have I completely misunderstood?