Guess what’s not a question. It’s this headline on the home page of Yahoo! TV:
That’s an imperative sentence starting with guess, which is a command to the reader, not a question.
Guess where the mistake is on the home page of Yahoo! Movies.
It’s that question mark at the end of an imperative sentence.
There are four kinds of sentences: One is the declarative sentence. Do you know what an interrogative sentence is? Tell me what an imperative sentence is. That’s not an exclamatory sentence!
Why is there a question mark at the end of this sentence on Yahoo! Makers? And how can a dimmer reduce overall energy output?
Great questions! The answers lie with a basic misunderstanding of English by the writer. The first has to do with a question embedded in a declarative sentence. The question is: Why is this so crucial? And some style experts would allow a question mark mid-sentence, like this: Why is this so crucial? you might ask. Looks weird to me. A better solution in my mind would be to recast the sentence: You might ask why this is so crucial.
On the second issue, the writer confused the word output with consumption or usage. At least, that’s my charitable view.