How to tell how much sugar is in these wines?

[quijote]

Here's a follow-up question to the main question above: In general, can one make a deduction about a wine's sugar content on the basis of the percentage of alcohol (as listed on the bottle)? This seems to be Andrea Immer's point in her intro book. It makes sense, as (in still wine) higher alcohol level generally means that more sugar has been converted into alcohol, and lower alcohol level would mean that less sugar has been converted into alcohol.

Is this a reasonable guideline? It seems to make sense, but I'm very much a newbie, so I don't know what kinds of exceptions there may be. (And the answer probably relates to the type of grape used, too?)

Q