You are on the right path.
I was not on the right path, I was exactly right. I stated the usage of
the words where I grew up and stated that this was the case. Unless you
grew up in Hadleigh, Essex, England or have a reference to English usage
in that area you are not in a position to contradict that.
"Doubt" expresses very clearly that
there is uncertainty about something.
I did not say that it means that something is definitely wrong/bad.
Note that my dictionary, "Either the most relevant or the most general
meaning is given first," so as the first meaning given agrees with me...
| doubt (dout)
| v.t. --- verb, transitive
| 1 To hesitate to accept as true; hold as uncertain; disbelieve.
That matches what I said
| 2 Obs. To be apprehensive of; fear.
Not what either of us is talking about.
| v.i --- verb, intransivitely
| 3 To be in doubt; be uncertain.
So, "Fred is in doubt," could have the meaning you would ascribe to
it.
| 4 To be mistrustful.
| n --- noun
| 1 Lack certain knowledge; uncertainty regarding truth or reality of
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
something
Still close on what I was saying.
The synonyms start with, "distrust, mistrust," which agrees with me as
well.
"Question" highly
suggests the same uncertainty.
No, the definition of question starts
| n --- noun
| 1 An interrogative sentence calling for an answer
Not mentioned under doubt. It continues in that line until
| v.t --- verb, transitive
| 1 To put a question or questions to; interrogate.
Then goes on with
| v.i --- verb, intransitive
| 1 To ask a question or questions.
So question is mainly an interrogative where as doubt is an expression
of mistrust in what is doubted.
Problem is often, but not always, neutral but meens something different
again.
| n --- noun
| 1 A perplexing question demanding settlement, especially when
| difficult or uncertain of solution; also any puzzling
| circumstance or person.
| 2 /maths/ A proposition in which some operation or construction
| is required, as to bisect an angle; anything proposed to be
| worked out.
This second usage is the one I would most expect with reference to C,
although the first is also possible.
The dictionary does not mention problem being a verb.
I have a doubt with these two lines of C.
Not a phrase that would be used where I grew up. The closest would be
something like, "I doubt it." A phrase which, to me, clearly indicates
disbelief although it does not indicate certainty that something is
wrong.
I have a question with these two lines of C.
Again, not a way of phrasing things I have heard from native English
speakers. "I have a question about these two lines of C," would be the
closest, and indeed neutral. It is also much closer to your phrasing
than I would ever expect to hear than you is the case with you example
of doubt. It does not imply that there is anything wrong with the two
lines of C, just that the questioner wishes to know more about them.
I have a problem with these two lines of C.
Only the last one suggests the lines of C are okay and the
uncertainty is only in the mind of the speaker.
This is the only one of the examples you provided that sounds natural,
however when expressed like that it actually implies that you believe
something is wrong with those lines of C which needs to be solved. Note
that all the definitions of problem include the requirement for action
to be taken (hence the implication of something wrong in the case)
rather than a requirement for information to be provided.
The neutral usage of problem is of the general form:
I have a problem, how do I sort an array of numbers in to descending
order?
There is a problem with my car pulling to the left at speed.
For your homework, I want you to solve the following problems...
The dictionary I am using is The New International Websters
Comprehensive Dictionary Of The English Language, Deluxe Encyclopedic
Edition, 1996 Edition. This dictionary tends to agree with me about the
meanings of doubt, question and problem and, as I said, I know the
definitions of these words from the perspective of a native English
speaker who has grown up in England. I would therefor say that the use
of the word doubt to mean question is a difference in usage to that in
England (for all I know it could be a common where you are) and one
likely to lead to confusion. It is also aggravating (to me) because it
sounds unnatural (to me) and I am therefor likely to be less helpful if
I am in a rush, although I do try to avoid letting poor English from
non-native speakers from affecting my response.