Partial negation is tough for me.
Are the following sentences partial negation or total negation? Or what does the following sentences mean?

#1. The sky is not cloudy all day.
I think #1 means there are no clouds sometimes, i.e.#1 is partial negation.

#2. Sue doesn't love him because he's poor.
I think #2 means the fact that he is poor is an absolute or very important reason Sue doesn't love him, i.e.#2 is total negation.
That song always bugged me. It's completely ambiguous. I'm sure the composer meant, "All day long, there's not a cloud in the sky!" But there's nothing wrong with taking it your way. Anyone who writes a line like that deserves to be misunderstood!

Your second sentence is ambiguous as well. At least with this one we can make our intention know through inflection, if it's spoken.

I'd say your interpretation would be total negation.

But maybe Sue has a passion for poor people. Just not this time. "Sue doesn't love him because he's poor; she loves him because he's such a great listener."

I'd say this version is also total negation.
How interesting!!

When you see #1 and #2, which meaning comes to your mind first, #3 to #6?
#3 and #5 do?

#3. There is not a cloud in the sky all day long.
#4. There are sometimes some clouds in the sky.

#5. Sue doesn't love him. Because he's poor.
#6. Sue loves him not because he's poor.
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I'd go with #3 and #6, but mainly because there's no context, and I have to make one up which suits me. I see no real reason to choose one over the other.
How interesting!!

The sky is not cloudy all day.
Sue doesn't love him because he's poor.

Welcome to "Ambiguity in English"! Emotion: smile

The context of the first sentence is a song which lists the merits of a particular geographical area. In that context, the sky is never cloudy.

One of the two interpretations possible for the second sentence can be eliminated (in the absence of a contradictory context) because Sue would probably not be more likely to fall in love with a poor man than with a rich man. Now if the sentence read,

Sue doesn't love him because he's rich.

then you'd have, in all probability, the alternate interpretation.

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Hello CalifJim,

Thanks for your detailed reply.

My English is so poor and I'd like to confirm.
Do you mean #6, not #5, comes in your mind first when you read #2?