Student or Learner
Do you find the following sentence is acceptable English?
He remarked how hard telling anything without revealing a part of the plot was.
If not, any suggestion, please?
It depends what you mean by acceptable. I understood the meaning straight away, so in that sense it's acceptable.So this "was" at the end is not acceptable?
Bhai's version is miles better, though, and is the one you should use.
But the question was "Did he actually remark ...?"
Did he speak? Did he actually put it in writing? If so, then I agree that we say "He remarked on [the subject]".
Usually, we only use "remarked" without "on" if it is followed by something in direct speech:
He remarked "It's very hot today."
He remarked on the heat.
He remarked 'How difficult it is...' - direct
He remarked on how difficult it was... - indirect
PS Of course, you can't hear quotation marks, so you might hear /hi:rɪ`ma:kt hɑʊ`dɪfɪkəlt ɪt ɪz/..., because intonation makes it clear that these are the actual words